iTopSpin
Current Posts => Collecting, Modding, Turning and Spin Science => Topic started by: andydecleyre on July 19, 2019, 04:36:34 PM
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Hello!
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The first top I really appreciated was the "top-no-sis" / "LSX" -- meant to spin as long as someone properly tilts a surface underneath it. The older models had a more normal top shape, which I preferred, but the newer ones have a tulip-like shape. I can't find any photos of the original. In order to work like this, it's spun on (what at least appears to be) the handle (upside-down).
I was recently gifted an aluminum ForeverSpin top. I didn't think much at first, but then I found that spinning it upside down proved it capable of the same feat: tilt the surface, keep it spinning.
What other tops do or don't have this property? If anyone has another material ForeverSpin, can you test it? I'm especially curious about the the tungsten carbide one.
Thanks for any info!
P.S. I just found http://www.ta0.com/tricks/plate_regen.html -- So apparently this called "regeneration" or "plate regeneration" and can be done with a Spintastics Hollow Point. I'm still looking for more (especially pocket-sized)!
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I appreciate your interest in this. For a while, I really got into lug nut covers used for large trucks. They are readily available and not very expensive. I practiced for a while and then tried to go past the "record" set with top-no-sis. Here is my post on the "thread about the longest spinning top".....
Thanks to a TV series called "How the States Got Their Shapes" I am not bored out of my mind. I watched several segments of that show while spinning the metal lug nut cover in an IKEA bowl. What a great show. It seems that I learn a lot every time I watch it. I finally let the spinner stop whirling after 3 hours 3 minutes and 53 seconds. The seven hour attempt is still out there with that whip top but I think it would take quite a few more good shows on the TV for me to consider that. Besides, I was really starting to get kind of dizzy the last hour.
Time for some lunch and a good walk to get my body back on track.
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I came up with the name "plate" regenerations while filming a video about the Top-no-sis and I think it's very appropriate.
I suspect the mushroom shape of LSX was mostly about marketing. The top only needs to have a rounded tip that is relatively large with respect to the size of the top.
Are you sure there was a Top-no-sis with a different shape than the Mushroom?
(http://ta0.com/museum/images/other_tops/Top-no-sis_LSX.jpg)
I just tried it with a few finger tops that looked promising.
The champion by far was the Japanese Taorenado:
(https://spingear.jp/images/detailed/28/TAORENADO_1.png)
It's an excellent plate regeneration top.
I also tried the Janus: it works, at least right-side up.
(https://s3.amazonaws.com/ksr/projects/1201642/photo-main.jpg?)
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I was recently gifted an aluminum ForeverSpin top. I didn't think much at first, but then I found that spinning it upside down proved it capable of the same feat: tilt the surface, keep it spinning.
I tried with my gold-coated stainless steel Foreverspin (first generation) and I didn't find it easy to regen upide-down.
You can get the Taorenado from Spingear:
http://spingear.jp/index.php?dispatch=products.view&product_id=2549
Although it regenerates very easily in the precession direction, not so in the opposite direction. The LSX is better in that regard.
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Thank you both!
Are you sure there was a Top-no-sis with a different shape than the Mushroom?
Yeah, the earlier models came to a nice point, so it could be spun "normally" as well.
The champion by far was the Japanese Taorenado
I just watched the video on that spingear product page for it and oh my goodness that looks too fun. I'm very tempted.
Although it regenerates very easily in the precession direction, not so in the opposite direction. The LSX is better in that regard.
Is it really possible for the LSX to regenerate in the "wrong" direction at all? I thought the best it (I) could do was withstand it for a while before going back with the spin.
I also tried the Janus: it works, at least right-side up.
Cool! This is much more common than I thought. The brim is so low on the Janus I'd think it hard to tilt without toppling.
I tried with my gold-coated stainless steel Foreverspin (first generation) and I didn't find it easy to regen upide-down.
Do you think it was the weight (for its shape)? Friction? My aluminum one is pretty slippery on some surfaces.
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Are you sure there was a Top-no-sis with a different shape than the Mushroom?
Yeah, the earlier models came to a nice point, so it could be spun "normally" as well.
I don't think it would work for a pointy top. But perhaps they were a little sharper than those of the tulip-shaped tops.
Although it regenerates very easily in the precession direction, not so in the opposite direction. The LSX is better in that regard.
Is it really possible for the LSX to regenerate in the "wrong" direction at all? I thought the best it (I) could do was withstand it for a while before going back with the spin.
Yes, even the instructions for the Top-no-sis say that.
(https://i.ibb.co/kSXwfY8/image.png)
For the normal direction (revolution and spin in the same direction), the top leans towards the center of the circle and the tip rubs the surface on the interior side.
For the opposite direction it needs to rub on the outside: you keep the top about vertical but incline the plate a lot.
I tried with my gold-coated stainless steel Foreverspin (first generation) and I didn't find it easy to regen upide-down.
Do you think it was the weight (for its shape)? Friction? My aluminum one is pretty slippery on some surfaces.
It might be lack of practice. I'll try again later.
You need to see this video that we have discussed before:
https://www.youtube.com/watch?v=tAFagoHmSQ8
:o ;)
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I don't think it would work for a pointy top.
Well yeah, there was no regen ability with the pointy end.
Yes, even the instructions for the Top-no-sis say that.
Those directions do not explicitly make the claim that backwards revolutions can regen, but I'll take your word that it's possible, and give it a try. Thanks for the tips!
In my drooling over the Taorenado, I saw that video of the BilletSPIN Loki, which looks fantastic. But aside from being out of my price range for a top, it's not readily available.
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This will regenerate in either direction......
https://www.4statetrucks.com/wheels/semi-truck-nut-covers_3521.asp
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Welcome, Andy!
Anyone: How much do the maple and birch LSX tops weigh?
Reported densities for these woods vary quite a bit, but all are <75% the density of water.
Modeling the LSX to test a hunch about its absolute AMI, AMI per unit mass, and TMI/AMI ratio. Experiments with LEGO tops point to these as key parameters for efficient plate regen.
Here, AMI = axial moment of inertia (about spin axis) and TMI = transverse moment of inertia about tip contact.
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Anyone: How much do the maple and birch LSX tops weigh?
I'm guessing the golden and brown LSX tops are of the same wood but just painted differently.
Anyway, I measured 13.5 g for the golden and a brown one and 15.3 g for another brown one.
Those directions do not explicitly make the claim that backwards revolutions can regen, but I'll take your word that it's possible, and give it a try. Thanks for the tips!
I'm still working on getting back the technique for backwards regens. I am regenerating some but not yet indefinitely.
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You can get the Taorenado from Spingear:
http://spingear.jp/index.php?dispatch=products.view&product_id=2549
Although it regenerates very easily in the precession direction, not so in the opposite direction. The LSX is better in that regard.
I need to correct myself. the Taorenado can regen well when revolving opposite to the spin: I can keep it going indefinitely in both directions.
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Thanks!
How much do the maple and birch LSX tops weigh?
I'm not sure which one I have now, but it's wooden (and tulip-shaped), and measuring around 15 grams on a kitchen scale.
This will regenerate in either direction.
Excellent! Thanks for the find, and the direct link (and bargain)! Any tips on the "reverse" regeneration technique?
the Taorenado can regen well when revolving opposite to the spin: I can keep it going indefinitely in both directions.
:o I really want that. Thank you! You make it sound easy. I thought I was good with the LSX, but never even thought reverse regen was possible based on my attempts. Do you think there's any chance of the steel model becoming unavailable in a year?
I'll also note that when regenerating with the aluminum ForeverSpin (upside down) vs the LSX:
- I generally have to tilt more aggressively
- I think its lower friction can make it harder to achieve the regen-grip, so high friction surfaces help, and big ones to allow for some non-regen sliding along the way
- I often fail the initial landing
- I often fail trick landings
- Its brim (there's probably a proper term for the top's widest perimeter . . .) is much more likely to hit the surface and abruptly conclude the spin at extreme tilts
.
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Thank you! You make it sound easy. I thought I was good with the LSX, but never even thought reverse regen was possible based on my attempts.
My recollection is that I could regenerate backwards with the LSX but I'm having trouble right now and only can extend spins by about 50%. With the Taorenado I can keep going and going and going. So, it's actually hard to do with the LSX.
No luck regenerating (forwards) with the inverted steel Foreverspin, yet, but I haven't tried much. Mine is first generation and they made changes on the second gen, including the stem:
(https://i.ibb.co/sJKMgvR/image.png) (https://ibb.co/sJKMgvR)
Do you think there's any chance of the steel model becoming unavailable in a year?
Foreverspin will continue in business for a while, I bet. So the steel version should be available in an year.
I will try with a different surface, as you suggest.
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Ah, I wouldn't be too surprised if the new-style longer stem and whatever they did to the spindle makes an important difference. Giving it the necessary tilt may just bring that brim right down to the surface.
As for the steel model, sorry, I actually meant the steel Taorenado. My wife has this wild idea that I don't "need" another top until my birthday.
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My wife has this wild idea that I don't "need" another top until my birthday.
My wife has similar wild ideas about the "impractical" things I keep buying. I no longer bother with "But honey, what about all those shoes??", as her game is "the best defense is a good offense".
So I pretty much ignore the protests, and the house keeps filling up with tops, LEGO, and shoes. In the end, no one wins and everyone wins. Perfect!
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Just posted a video of my LEGO version of "plate regeneration" here (http://www.ta0.com/forum/index.php/topic,5846.0.html).
After looking closely at the regeneration process, I've decided to call it "rock 'n roll regeneration" (RRR) -- partly cuz it works even better in bowls, and partly cuz that's what actually goes on: You keep rockin' the arena, flat or concave, just so, and the top keeps rollin' downhill, picking up speed along the way.
Still not very good at RRR, but it's a very enjoyable multisensory experience with interesting things to see, hear, touch, and sense with your whole body. Highly recommended, and something you can engineer on your own.
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Partly cuz it works even better in bowls . . .
Are you sure? I have not tried it myself and I know it's in the 1965 patent, but my guess is that it will force you to lean the top even more, making it harder. But a bowl should help with the counter-spin/precession regens. I'm away from most of my tops this weekend, so I cannot check it.
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Partly cuz it works even better in bowls . . .
Are you sure? I have not tried it myself and I know it's in the 1965 patent, but my guess is that it will force you to lean the top even more, making it harder. But a bowl should help with the counter-spin/precession regens. I'm away from most of my tops this weekend, so I cannot check it.
Warning: This is way too long a reply, but it's complicated stuff -- at least to me. It'll all make more sense when you see the video (coming soon).
Maybe I should clarify "works better". Let's generalize to "rolling regeneration" (RR), wherein you boost spin rate by somehow manipulating the arena, flat or otherwise, to force the tip to roll while the top is free (i.e., not held in your hand, as it would be with a wizzzer). We'll come back to how you move the arena to make that happen.
In the RR in a circular bowl I've tested, you give the top a good vertical twirl on the bottom of the bowl and then coax it into orbiting the vertical through the bowl's center without trying to lean it over at all. Looking down from above, the orbital direction will be opposite that of spin, as the rolling contact will be outside the top's spin axis. (You clearly anticipated this dynamic, as it corresponds to the "counter-spin/precession" you mentioned.)
You get into a state of pure rolling almost immediately with this method. When you pump the bowl for constant orbital speed, the tip rolls along a circle of fixed radius inside the bowl. Otherwise, it rolls along a slowly opening or closing spiral with little radial velocity. (Think fast car on a banked circular track.)
If you gave the top enough angular momentum at the outset, gyroscopic action will keep it more or less vertical the whole time. This gyroscopic "stiffening" of the top's orientation means that when centrifugal force (CF) pushes the top's CM outward, it also presses the tip onto the bowl's inner surface, thus increasing the normal reaction force on the tip at the point of contact.
Since friction and rolling resistance both grow with normal force, the CF effectively boosts traction -- which boosts the maximum regenerating torque achievable by pumping the bowl -- which boosts the spin acceleration rate (if you pump correctly) -- which boosts both orbital radius and speed (since we're now rolling without slipping on a banked track) -- which boosts the CF and normal force even more.
This neat positive feedback loop is broken only (a) when the user backs off on pumping the bowl, or (b) when the tip climbs over the rim. In the latter case, the top flies off, still spinning upright, and the bowl's become a top launcher! And a pretty powerful one, too. (To control launch direction, you just spill the bowl before the top escapes on its own.)
Hence, RR "works better" in a bowl than on a flat arena in that it's much more effective at accelerating spin rate and also capable of achieving much higher spin rates. And the bowl's at least as much fun.
But now I'm thinking that I shouldn't have called RR in a bowl "rock n' roll regeneration". Yes, in RR on a flat arena, you move the arena with a rocking or combined rocking+circular motion with a definite vertical component either way. But RR in a bowl works only when you move the bowl horizontally in a circular or back-and-forth motion with no vertical component.
So if "rocking" necessarily implies vertical motion, we should either reserve "rock n' roll regeneration" for flat arenas or just use "rolling regeneration" to cover flat arenas and bowls alike. I plan to do the latter from now on.
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So, with the bowl you are achieving counter-precession regenerations. But are they easier than the forward-precession regenerations on a flat plate? Can you achieve at all forward regens in a bowl? Is there an ideal shallow bowl in which forward and counter regens are equally easy? I need to re-read the 1965 patent and see what it says. Note that you can replace "precession" by "spin" in the name, but counter-spin regenerations sounds paradoxical.
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Behold my gyrocyclotron -- a gyroscopically stabilized high-energy rolling top accelerator. Here you see my only workable bowl and one of my best LEGO gyrocyclotron tops...
(https://i.ibb.co/q57WLkm/20190818-110916.jpg)
Before answering your questions, wondering if the top's orbiting motion about the bowl's vertical centerline is really a gyroscopic precession in the usual sense? The top's nearly constant small inward tilt while orbiting is surely maintained gyroscopically. But the orbiting itself seems more like just rolling tip travel around a banked circular track.
So to be safe, I'm sticking with "orbiting" for now.
So, with the bowl you are achieving counter-precession regenerations.... Can you achieve at all forward regens in a bowl?
Exclusively, and really doubt it, resp. But if anyone could pull off high-speed forward regens in a bowl, it would be you.
If the top is to orbit the bowl by rolling without scraping at high speed, I think the rolling contact pretty much has to be outboard of the spin axis. And that means an orbital direction opposite spin. In my hands, trying to make the top orbit the other way instantly kills its spin, and it goes down with a thud.
But are [regenerations in the bowl] easier than the forward-precession regenerations on a flat plate?
Much easier, and I am to skill toys as canaries are to mines: The smallest challenges trip me up. :o
The only tricky part is sustaining max orbital speed -- and hence max spin rate. This occurs just before the tip climbs over the rim, and that's best avoided by listening closely to the whining sound made by the tip on the bowl.
Is there an ideal shallow bowl in which forward and counter regens are equally easy?
You're right in thinking that the bowl can't be too deep for its diameter. But too shallow is just as problematic. I'm having a hard time imagining a bowl that would make forward regens possible while containing the top well enough to achieve the high orbital speeds I'm getting.
This circular serving bowl works beautifully. The other 9 I found around the house didn't work at all. For starters, most had inner bottom flats. The initial transition from spinning top to spinning+orbiting top is almost spontaneous when the bowl's inner bottom is curved but fails with even a small flat.
(https://i.ibb.co/BshDLQ4/20190818-110554.jpg)
The inner surface closely approximates part of a sphere of radius R = 126 mm, and its depth is only 54% of that. The aperture is 224 mm across. The slope at the inside rim is ~25° from vertical, and any workable top must have a scrape angle a good bit smaller than that. That means a rotor packing a lot of AMI into a relatively small maximum radius with a lot of clearance underneath. Hence the wide but thin high-density rubber tire and long black tip holder to its right.
You need a ball tip with some grip, and the larger the top's AMI, the larger its maximum radius of curvature must be. This small hard rubber tire makes a perfect tip for the high-AMI top shown. The tread lets you gauge orbital speed by ear, and that helps you bring the tip right up to the rim without going over.
(https://i.ibb.co/mT3Qdsj/20190818-110829.jpg)
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Interesting bowl. We have been using IKEA bowls for a number of these activities.
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Interesting bowl. We have been using IKEA bowls for a number of these activities.
Dug this fine vintage Melmac bowl out of some old camping gear boxes in the garage. Gotta be at least 30 years old.
What do your IKEA bowls look like, and how do you use them?
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This seems like a lot more than what we paid for these bowls but this looks like the shape.
https://www.amazon.com/IKEA-HULTET-Dish-bamboo-30/dp/B00GMMC2M4/ref=asc_df_B00GMMC2M4/?tag=hyprod-20&linkCode=df0&hvadid=309705949620&hvpos=1o5&hvnetw=g&hvrand=10803752456574111859&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9015781&hvtargid=pla-714545297887&psc=1
There was a smaller bowl and a larger bowl years ago.
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We got started on this bowl from this classic spinning top circus video. I think johnm was the one who pointed me to the IKEA sale.....
https://m.youtube.com/watch?v=LDXAhwhsZ9k
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This is interesting. Unfortunately, I discovered that I don't have suitable bowls. Ikea opened a shop over here several months ago. It's time I give it a visit.
I re-read Martin's patent:
(http://ta0.com/museum/images/patents/US-Pat-3191341_rock-n-roll-regen.jpg)
It covers both bowls and flat plates. However, it explicitly mentions that the spin and orbit directions have to be the same. So it only covers forward regens.
Before answering your questions, wondering if the top's orbiting motion about the bowl's vertical centerline is really a gyroscopic precession in the usual sense? The top's nearly constant small inward tilt while orbiting is surely maintained gyroscopically. But the orbiting itself seems more like just rolling tip travel around a banked circular track.
So to be safe, I'm sticking with "orbiting" for now.
I was mentioning precession just to define the direction of the orbit as forward or counter. For the counter the top mostly remains vertical and precesses little. However for forward regen I am guessing that if you match the orbit period with the precession period you get the smoother movement.
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This is interesting. Unfortunately, I discovered that I don't have suitable bowls. Ikea opened a shop over here several months ago. It's time I give it a visit.
I re-read Martin's patent: It covers both bowls and flat plates. However, it explicitly mentions that the spin and orbit directions have to be the same. So it only covers forward regens.
Martin's bowl looks like it's shallower than mine. I'll have to try to find one like it. Does the patent give measurements?
Wonder how fast he got his top to orbit and spin in the bowl? In one video I timed, the black and white top above turned in maximums of ~1.3 m/s in orbital speed and ~1,200 RPM in spin rate with the tip as close to the rim as I dared. The initial spin rate was maybe 40% of that. A skilled player could have sustained these speeds indefinitely.
For the counter the top mostly remains vertical and precesses little. However for forward regen I am guessing that if you match the orbit period with the precession period you get the smoother movement.
Just what I've observed, both on flat arenas and in the bowl.
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We got started on this bowl from this classic spinning top circus video. I think johnm was the one who pointed me to the IKEA sale.....
https://m.youtube.com/watch?v=LDXAhwhsZ9k
Thanks, Mike! Never tire of this video. Will be ordering one of those bowls. Maybe it's shallow enough for the forward rolling regens ta0's interested in. Just hope it's steep enough to contain the high-speed reverse rolling regens I've been doing with my steeper bowl...
https://www.youtube.com/watch?v=WA67H3hJAY0
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Anyone: Confused now about the IKEA bowl's inner surface. How smooth is it?
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Are you sure there was a Top-no-sis with a different shape than the Mushroom?
I found an old board for the top-no-sis with a photo of the old-style LSX:
(https://i.ibb.co/jVYJCzZ/IMG-20200120-172311.jpg) (https://ibb.co/jVYJCzZ)
EDIT: Just ordered the Taorenado, woohoo!
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The first top I really appreciated was the "top-no-sis" / "LSX" -- meant to spin as long as someone properly tilts a surface underneath it. The older models had a more normal top shape, which I preferred, but the newer ones have a tulip-like shape. I can't find any photos of the original. In order to work like this, it's spun on (what at least appears to be) the handle (upside-down).
Thanks for sharing that photo. I can see that it had to be spun on the "handle" for regenerating, as the other side is too pointy.
I think you'll like the Taorenado.
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EDIT: Just ordered the Taorenado, woohoo!
Is small and not beautifull but is amzingly relentless, magic!!
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EDIT: Just ordered the Taorenado, woohoo!
Have you seen this review?
https://youtu.be/Q440ijHBH9M
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But RR in a bowl works only when you move the bowl horizontally in a circular or back-and-forth motion with no vertical component.
Be careful with the word "only". All broad statements are wrong! :) In a bowl, orbiting the same direction of spin is pretty easy. Tilting is not necessary. However starting from a slow spin is lots easier with tilting. As orbit speeds (and thus spin speeds) increase tilting the bowl is needed to keep the top in.
Using the Bowl at the Hall of Fame I have been able to keep 2 tops going for a little while.
It is possible to orbit the other way (like a flat plate) by staying near the center.
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Be careful with the word "only". All broad statements are wrong! :) In a bowl, orbiting the same direction of spin is pretty easy. Tilting is not necessary. However starting from a slow spin is lots easier with tilting. As orbit speeds (and thus spin speeds) increase tilting the bowl is needed to keep the top in.
Using the Bowl at the Hall of Fame I have been able to keep 2 tops going for a little while. It is possible to orbit the other way (like a flat plate) by staying near the center.
Agree, too broad. But true at least for the bowl shown, with its smallish diameter and strong, uniform curvature. It's pretty much a one-way RR arena. Also, the only workable bowl out of many I tried around the house.
Are you referring to Mike's bamboo bowl from Ikea? What's the finish like? Gloss or matte, like our bamboo utensils? Maybe I'll spring for one.
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Are you referring to Mike's bamboo bowl from Ikea? What's the finish like? Gloss or matte, like our bamboo utensils? Maybe I'll spring for one.
Yes. it is large and shallow. Matte finish.
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Thanks for the extra Taorenado video. I have mine in hand, and it's wonderful. Is the name supposed to be a play, with "tao," or is it simply from a transliteration of "tornado" into Japanese, or what?
As it's around my birthday, I've also managed to get in touch with Ed Rubin, LSX/top-no-sis inventor, and will be getting some more of the old, pointed ones very soon. He's retired, but still has stock available, and will probably accept more orders via email and payment by mailed check or money order -- edrubin17 AT gmail DOT COM (mangled to throw off any spam scrapers).
Oh, and I'm starting to get the hang of reverse regeneration, though I still find myself jerking erratically and losing control much of the time.
Thanks so much to everyone for existing and hanging around here!
Now my regeneration collection is (or will soon be):
- Foreverspin aluminum
- LSX tulip
- LSX pointed
- Taorenado
I guess the ones to dream about now are:
- those nut covers
- Foreverspin tungsten carbide (just for durability, but probably will never be willing to spend for it since I've got the aluminum)
- Billetspin loki (but: not available, expensive, no confirmed regeneration)
That Billetspin release policy (available for only a few days and then never again) is maddening.
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Thanks for the extra Taorenado video. I have mine in hand, and it's wonderful. Is the name supposed to be a play, with "tao," or is it simply from a transliteration of "tornado" into Japanese, or what?
It's just a cool coincidence: the verb taoreru means to fall. Taorenai is the negative: will not fall.
The ending was probably made to match tornado.
:D
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You can make some cheap and fun little LEGO tops with Taorenado-like behavior and experiment to see what it took to tune that behavior into the design. Configurations with especially strong self-righting come in at 3:18 and 6:18...
https://youtu.be/D_btrG34M0Q
Two key ingredients: A fairly high center of mass and a ball tip with the right radius of curvature.
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Beautiful stuff in that video, Jeremy, thanks. I'll have to keep an eye out for Lego sets like that next time I get some "for the kid."
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Beautiful stuff in that video, Jeremy, thanks. I'll have to keep an eye out for Lego sets like that next time I get some "for the kid."
Alas, there are no sets like that -- and in fact, very few LEGO top sets ever offered. Some of the recent Airjitzu and Spinjitzu sets in the Ninjago line are notable exceptions, but the parts useful for making your own tops aren't very versatile.
Just rummage through the kid's parts and see what opportunities present themselves. Get any additional parts you might need from www.bricklink.com. That's where all the parts in my videos here came from.
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Good info, thanks. Well we haven't yet moved on from Mega Bloks, and don't have any proper Legos at home. Maybe I'll investigate alternatives like Ocho/KuckleStrutz (https://connectabletoys.com/) and K'NEX (https://www.knex.com/) for the next stage.
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Good info, thanks. Well we haven't yet moved on from Mega Bloks, and don't have any proper Legos at home. Maybe I'll investigate alternatives like Ocho/KuckleStrutz (https://connectabletoys.com/) and K'NEX (https://www.knex.com/) for the next stage.
If you change your mind, my blog page at http://www.moc-pages.com/moc.php/431164 (http://www.moc-pages.com/moc.php/431164) will show you a versatile and relatively inexpensive way to get started with LEGO tops -- one you can build on and tinker with as new parts come in.
The blog page includes lots of photos, videos, and direct links to all of the key parts in the BrickLink parts catalog at http://www.bricklink.com/catalogTree.asp?itemType=P. (I buy all my parts on BrickLink.).
With shipping, you could probably make 10 of the tops featured for well under $30 with parts to spare.
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Finally sprung for a shallow laminated bamboo bowl like the one from Ikea. Got it on Amazon, so it may not be exactly the same.
Intended to use it for rolling regen (RR) and lateral spin transfer (to balls orbiting the top). Workable but somewhat disappointing so far.
Pros: Large diameter, lack of lip, promising inside curvature with no bottom flat.
Cons: Low-friction inside surface covered with low, closely spaced ripples from the lamination -- as if they forgot to sand it.
Tip traction suffers from both the low friction and the ripples, which cause my tips to hop during RR. Since the ripples spiral slowly outward, a top orbiting at constant radius has to cross one or more ripples with each circuit.
Will try to optimize a top for RR in this bowl. Sorely tempted to sand down the ripples.
Again, this could be a cheap knock-off of the Ikea bowl Mike and others have.