You know, I just used scissors and started with small holes to see how the top fit. Then, little by little, I enlarged the hole until my case could close. Actually, my holes are still a little too small but I can force my case shut and nothing EVER rattles in it. I made conical shaped holes.....except it was a four sided conical shaped hole, not rounded. I don't know what what that name of that shape would be called. I'm sure ta0 and JohnM know. It was like four triangle shapes.