I screwed up. Over break I took a miniature flower pot and ground out an opening in the side and turned it upside down for my aquarium. It was adorable: a little cave for my Betta to hide in.
Unfortunately tonight my Betta freaked out while in the cave and tried to go out the hole in the bottom of the pot. It didn't work and he got himself stuck. I tried to break apart the pot, but couldn't and finally managed to work him out. He lost a large patch of scales on the top of his body and most of his front fins are mangled.
After some experimentation, I've figured out that using a philips head screwdriver to chip out the pottery works 100xs better than my Dremel anyways. Go figure.