This was a round of experiments in getting from a 3D-printed figure to a wax one, as a step toward casting it in metal. The point of the wax is that it can be burned out of a plaster mold. I could go straight from the printer to plaster, but SLA print resin makes all sorts of soot and ash, and it expands when it burns, which would ruin the plaster. So the wax copy is the way around that.
The wax bust above is where the experiments ended up. I have an entire YouTube series on this subject.
Silicone mold (August 2021)
The first route was a silicone mold. Here's the 3D-printed resin bust of Leonardo da Vinci, the blue silicone mold, and a yellow wax copy made from it. Next stop was going to be a plaster cast of the wax figure.
Caulk as casting silicone (September 2021)
You can buy two-part casting silicones, but they're expensive and go bad quickly once opened, which makes them a poor choice for occasional home use. So I tried hardware store caulk as a casting medium. Straight out of the tube it's too thick to work well, but I finally hit on a recipe that is thin enough to flow around a model, cures quickly, and uses only easily available, relatively safe stuff.
The cutaway block shows that I could get it to set without voids by using a vacuum chamber. The complete mold shows that it takes detail well.
Gelatin molds
Amazing Remelt is a good product for this, but I think a homemade version costs about a fifth as much. It's just glycerin and gelatin. Here's the first experiment: the printed mold halves, with a translucent red gelatin casting between them.
And a demold success, with a teal gelatin block holding the impression of the bust next to the resin bust it came from.
The mold parted cleanly along the layer lines. There are some voids from bubbles, so I might need to refine my technique there.
Wax (September 2021)
Pouring the wax in stages did the trick. There is one very small area, down at the bottom, where the heat of the wax melted the mold where it was thin, but otherwise it came out great.
I think I'm done with this line of experimentation.