You could cast ponies in resin. I've seen a few artists do that and there are some cool effects you can achieve with transparencies and glitter. Polymer clay could work too but it would be expensive unless you could figure out a way to keep the pony hollow or have a foil/wire armature inside of it. Then again I don't know how expensive resin is! For all I know the costs could be comparable.
Oh! Maybe cold porcelain? I don't know if you can use it with molds but it doesn't hurt to look into it :)
Polymer clay can be sanded and filled in so as long as you can get the seams mostly together it would be fine even if they're super messy or have small gaps or whatever.
Oh! I just thought of something! You could do an oven safe silicone mold in two halves and carefully fill each side with polymer clay, maybe add an armature inside. Once the two sides bake you could join them. This (https://thebluebottletree.com/best-glue-for-polymer-clay/) is a great article that covers different ways of gluing things to polymer clay. For this idea the section "Glue Polymer Clay to Polymer Clay" would be most helpful.
Polymer clay can be sanded and filled in so as long as you can get the seams mostly together it would be fine even if they're super messy or have small gaps or whatever.
Oh! I just thought of something! You could do an oven safe silicone mold in two halves and carefully fill each side with polymer clay, maybe add an armature inside. Once the two sides bake you could join them. This (https://thebluebottletree.com/best-glue-for-polymer-clay/) is a great article that covers different ways of gluing things to polymer clay. For this idea the section "Glue Polymer Clay to Polymer Clay" would be most helpful.
I like this idea! Thanks for the link :D still unsure about how to get the hair plugs though, that's gonna require some thought... unless you drilled in it. But polymer clay I would assume is a bit too hard and would risk cracking, wouldn't it?
I'm glad its helpful, Shaiyeh! And actually, polymer clay can take a lot of abuse as long as you use a good brand and bake (https://thebluebottletree.com/baking-polymer-clay/) properly! :D It can be drilled, sanded, painted, carved, all kinds of things. Some brands can even withstand hammer whacks or being run over by a car.
BBT is a really great resource for everything polymer clay, but this (https://thebluebottletree.com/best-polymer-clay-brand/) would probably be a good place to start! Cernit (https://thebluebottletree.com/review-of-cernit-polymer-clay/), Premo, or Fimo Professional would be the best options in my opinion but don't be afraid to try a few brands to see which you like best.