I’m practicing making molds. This one, of a sun prototype I made, is created with cornstarch, silicone caulk, some mineral spirits, color, and glycerin. I gave up measuring and just approached as I might in the kitchen assessing my dough for baking.
It came out alright. Yet, it was hell to create. I made the mistake of using a bucket to mix in. NO!! Mix it in the open on a tray, the fumes are horrendous and will burn your nose.
Rubber gloves are a good idea. I used latex medical type to have better sensitivity to the material. e in a cheap plastic tupperware type container large enough to shape the mold itself around the sculpture. It worked great. There is a real need to ensure there are no air pockets as they will tear when stretching the mold to release the shape.
This is my first mold, I know now that I need to get on the mixing a lot faster and use folding. Its not as easy for larger things. My prototype is about four inches wide and two deep. The dough was thick, so I tore it in parts and worked them down around the edges while the material was yet pliable. I trust the next attempt will be more confident.