I HATE PLASTER I don't do molds PLASTER HATES ME
The Instamold half of the idea worked.
The pouring of the plaster part worked. My experience with the heads taught me to pour the plaster while the mold was fresh or gravity would squish it.
And no matter what I do plaster hates me.
Please don't tell me how to do plaster. The heads I made this way came out. I want to believe it has something to do with structural issues with Roger's form. Instamold is like thick Jell-o, the original Roger released from a seam down his back and bum, I pulled the mold apart to remove the plaster positive. Sitting in the mold longer wouldn't have made a difference as my experiments with the heads proved. A two part mold wouldn't have helped as the Instamold would have stuck to its self. Any casting needs to be done while the mold is fresh because it shrinks and collapses with gravity a bit as it dries.
If I ever bother to use Instamold again it will be for push molds or smaller glove molds of heads. I have Mold Builder but with it's issues of sticking to its self I'm not going to try and get four legs and an undercarriage to release. I don't think I'm messing with Amazing Mold Putty, long story short I don't want the greasy mess on Roger.
Roger got his hooves and I shall proceed on his human half shortly.
*The problem is definitely with Roger's design, the Instamold and plaster would have worked. He released fine, the plaster poured without leaking, the mold peeled away. It appears the knobby Rigid Wrap knees on the original are what keeps him together. A 3 part mold would be best at this stage, one part under his tummy and inside of his legs and two for each half otherwise, would be the way to go but it's beyond my abilities at the moment. I can see a 2 part with Amazing Mold Putty, legs and belly in one half, back in the other, might work. This would need something to prop it up. AMP is rubbery, and greasy. I can see doing a glove mold all the way around his horse half, did this with some heads, then cutting a seam along the back to get him out. The problem comes with something to help prop the mold up for the pour and seam repair. Head molds I could hold in my hand, seams and any place that had got to thin tended to leak.
I've pretty much decided to finish Roger a he is. Any further Manimals will need to be done in a different way.