Jim the polyurethane and epoxy tooling boards are like rifles they come in all sizes ,shapes and colors. Each has it's unique feature, in the above photo the large board that the other pieces are setting on is a long established material called REN shape 450, it machines , carves ,sands fantastic the dust resembles Bondo . Freeman Manufacturing sells REN Shape and other similar tooling boards. I use this for larger models. The yellow block is Butterboard, same type material but is easier to carve and sand,this is usually my first choice when making models. Every model for casting the brass parts on my miniature Lancaster rifles were made from Butterboard. Mc Master carries butterboard but Golden West is the mfg. and you can sometimes buy drops very cheap from them.
The green stuff is yet another similar material, the reason for using this on the wheellock is it is stiffer and a little stronger than both Ren shape and butterboard.The grey block is what I used to make all the lock parts, this is Metapore and machines like cutting air however the finished product is extremly strong ,almost like powdered aluminum.The front piece is cellouse acetate which was the industry standard before the polyurethane and epoxy tooling boards came along, I will be making the model springs for the wheellock from this ,it will act just like a spring and return to the compressed shape when tension is released. Another great feature is it can be glued up and parts attached with acetone.The other boards can be built and pieced with normal glues as well as superglue.Shoot me an e mail and we can hook up on the phone if you need more info.
Paul