OK thanks guys for clearing this up for me.
My main objective was to iron out the inconsistencies in making the stock. Not so much the shape (which is the beauty of the thing and the "art") but the point at which it fixes to the support structure for the barrel.
I guess I'm gonna have to get better at the engineering side of woodworking!
How many stocks are you wanting to make? I see a heap of posts about wanting to mold and cast a part as a 1 off and I have to question the logic for the following -
1. First up, before you even consider molding casting, you NEED a master part to make a mold of. So many people I talk to seem to have missed that part.
Your master part can be pretty made from anything, but if you are only making 1, then your master is your part. End of story.
2. There is a cost to molding and casting materials that many I speak to people I speak to have not a clue about. They think molding silicone is the same as caulking silicone. Not it is not and whilst caulking silicone can work, it can be hit and miss so far as picking up all the details.
3. The volume of the mold is something people don't consider. Not sure what you guys pay for molding silicon in the US, but here in Australia, we are looking about $65.00/KG. To reduce the mount you need, a jacketed mold might be more suited. This is especially useful for larger parts.
4. Resins vary in both cost and performance. Cheap resin is, well cheap resin and may or may not give you the results you are chasing. Good quality polyurethane does cost more and you will get a better result, but the success comes down to you, how you work it and pour it.
There are plungers that sort of INJECT resins into large molds. Maybe that is what your thinking about?