Looks like a great idea. Thanks for sharing your progress and the problems you had along the way. Would baking parchment have been less likely to stick to the mints than wax paper? Tries Two and Three look very nice anyway. How long did you leave it in for in the end?
I think that parchment paper would have worked better. The linked tutorial did say that parchment paper was what the original person used, but it was quicker for me to pick up wax paper than search for parchment paper at the Commissary (Hubby is sick, didn't want to keep him too long at the store!)
cute idea, and I can see why you wanted to try it! Perhaps parchment would help, and what if you baked it in a round, square, or rectangular pan (cutting the parchment to fit) instead of a cookie sheet? I wonder if it would prevent odd shapes? It might even make for a slightly thicker (and therefore sturdier) tray as well. I may have to give this one a try!
Using a tray to fit would be a good idea, thicker is better but the trays were actually sturdier than I thought they'd be. You have to use some force to crack them.
In the end, I sat in front of the oven and kept an eye on them while I worked on other things. The tiny tray was about 4 minutes, and the final tray was 8, maybe?