Thanks to all the posters in this forum, I have a "crop" of 'tufa pots. Most of my molds came from the dollar store and Goodwill. But I wanted to make a modern-style planter and tried to make my own mold. As you can see in the pic, I used foam house insulation and a lot of duct tape. I had to destroy the inner mold to remove the planter. I used vegetable spray as a release agent. My question is; does anyone have a better idea?