I use a two part resin from Smooth-On called Smooth-Cast 310. I cast all the parts using silicone molds that I made. I also use Magicsculpt to fill in and smooth out areas on the figures where I shape the articulation points out.
Hit me up anytime with any questions, happy to help any way I can so fire away!
No problem. If you have any other question just send me a PM or something and I can either answer them myself or point you in the right direction where to find better answers, or at least try anyhow haha