I still haven't really gotten around to the real smooth sanding and "bondoing", but there's more parts to create in any case.
I ended up purchasing a scope, but other than that, I haven't bought anything for it. The blaster is made from wood taken from a scrap pile outside a box factory, some pvc I didn't need for my jet pack project, and a heavily modified Pringles tube with a type of plastic silverish looking film. Still not really attached, and I might up replacing it with something better. And the scope is slightly sloped I just noticed.
I am currently trying to make the back piece of the chamber, with the hammer and that.