Can you bolt up a synthetic stock into a duplicator and make a copy of it?

Can't see why not. If the forearms has a LOT of flex might need a rod or something to make it stiffer but can't see it as a big deal. If it has big gaps in the forearm they would need filling. Again no big deal.

Sure can. A lot of patterns are made of fiberglass so tthey last longer.

I've had several calls to copy the Echols Legend stock. As well as a few others.

To everyone that has asked me to do this on my machine, I tell them to provide me a letter from the manufacturer with their blessing to do this.

I never get a call back.

Some manufacturers may have no problem providing the letter. I don't know.