I would recommend that you get the thickest sole flip flop that you can find. That way it's easier to make longer dremel bugs like pencil poppers. To punch out the foam, I use bullet casings. I drill out the primer, slip in a 1/8th inch bolt so that the head is inside the shell casing, then I tighten down a nut on the back of the casing. I now have a great plug cutter that fits in any drill/drill press. I have these ranging in size from 22 caliber upto 50 caliber. If you have a shell that has a "shoulder" on it, simply cut it off at the shoulder. I also like to sharpen them up a bit which is very easy once they're in the drill. If you haven;t already done so, I recommend you read Jim Hatch's article on Dremel bugs on the site.

Good luck and don't be afraid to ask questions.

Jim Smith