To start off, you're obviously going to want to make copies of your "base" figure so you can begin sculpting on it. This is a great way to get into action figure building, because most of the science of joints and articulation is already done. Your first "waste" mold could be done in any rubber. OOMOO tin silicone is the cheapest rubber we produce, and it's a very forgiving product, so it's great to learn with. It's what I learned on back in the day.
Once your waste molds of your original figure are made, you'll want to pour in resin to give you something to sculpt on. You'll want a rigid resin for this, so your add-on stuff doesn't come loose. SmoothCast 300 is perfect for this. It's a rigid, white urethane resin that is great to work with. If you've never done molding or casting, we make a Starter Kit that includes OOMOO rubber, SmoothCast 300 resin, sealer and mold release. This will get you started with the basics of molding and casting, and you'll be on your way.
When you're ready for the finished product, you may want to graduate to a bit higher product line, depending on your needs. If you plan on doing many casts of your new sculpt (if you're going to sell garage kits), you'll want to shift to a platinum rubber, like MoldStar 15. The platinum rubbers are a bit more expensive, so you wouldn't want to use them for waste molds, but they have a far superior quality and shelf life, making them a better choice for production molds.
And while you could use SmoothCast for your final product, it is a rigid resin, meaning it has a lower impact resistance. A dropped figure may chip or break. A better product for action figures is SmoothCast 45D or 65D, both of which have varying degrees of impact resistance. They feel more like what you'd expect when you pick up an action figure, and they also flex slightly, meaning you won't break off thumbs when you try to fit weapons in the hands, etc.
Our site has a LOT of videos and step-by-step galleries on how to get started. If we can help you with any other advice, just ask!
