I could see them being made in a mold, aside from the butt plate, screws, and sling swivel. I don't think they would sell particularly well seeing as that anyone putting together an e. german kit would want an original stock... unless yours are that good. You would really have to nail down the look and feel if not the exact composition for people to be really interested. We need need more east german kits anyways.
There's an example of someone making spot on collapsible stocks for the colt 607 model and was pretty successful, but for some reason or another (couldn't source sling swivels or something??) he kinda stopped doing it, and now even those stocks command a premium. There's a kind of ebb and flow to these things and what will sell at a certain time. Kinda need the right thing at the right time, which would require paying attention to the market. Lots of other cool stuff that needs to be made, but keep in mind: anything you sell to put on a gun, may actually be put on a gun and it's got to work dude.
If you want to make one, I won't convince you not to. Sounds like a fun project.