Here is my first plaster piece after it has hardened. So far everything is good, with no shifting of that raised foreleg. (On small pieces, stabilizing the legs is the biggest challenge.)
I will need to shape this first piece, though.
Splitting the rubber gusset after it has been poured avoids a mold line on the rubber original, but the downside is a rough side where the two gusset pieces meet. I will have to smooth the area.
Here I’ve done the basic shaping for the area. What I want is a smooth transition from the edge of the leg (which I cannot disturb) to the other side. I also have to be careful not to create parts that are really thin. Plaster is a soft material, and thin or pointy areas tend to chip off once the mold is in use.
This is the other side of the front piece, and it shows why I needed to slope the cut back. If I had cut straight across from the other foreleg, I would have cut across this opposing leg. There is also a bit of my rubber sprue line visible, so I’ll need to sand that smooth as well.
Here is my finished front gusset. I can already tell that this piece is going to be the evil one for this mold, because there wasn’t any way to avoid some really thin, really pointy parts. But it is smooth, and I am pretty sure it will drop from the casting (rather than have to be wiggled off). I think it will work! Now all that’s left is to seal the non-design areas with mold soap.
Here I’ve inserted the properly shaped, soap-sealed front gusset into the master mold. In the next step I’ll be pouring the second gusset.
I’ve also taken out the poll piece so I can pour it without having to disassemble to mold. The general rules for small horses is never remove pieces you don’t have to, and take apart the mold as little as you can manage. That keeps everything in proper registration.