How specific do you need it to be? I mean, basically, a paintball marker starts out life as a block of aluminum, get's milled and honed to proper specs, drilled and tapped to proper specs, you bolt on some other parts, like a gripframe, barrel, etc,. that have been pre-milled, honed, drilled and tapped, then you stick in a bunch of pre-fabricated (in most cases) bits of aluminum, steel and electronics and Voila, a paintball marker is born. If you need specs like to what tolerances they are milled and honed, what machines are used, what type of aluminum is used, how the internal parts are made or where they come from, etc., then it gets rather complicated and depends a lot on the exact brand, make and model.