I'm working in Afghanistan right now, so aside from 'get a tax stamp', I've done nothing yet with this project (I already had the inerted/demil'd RPG2).
An RPG2, contrary to what you might think the name implies, has no rocket motor, and only a black powder launch charge. Black powder is much less energetic than smokeless. An RPG7 (and a Carl G), use smokeless (as well as the '7 having a 'sustainer' motor)... much more pressure, and complexity. Not going there.
Anyway, I'm going to make some projo's, and I'm going to use some original projo's. My launch motor will be the same spec as the original, so my propellant carts could be used on either original or my own homebrew projo. The primer is on the projectile, though, not the propellent cart, so it is a little more involved than it sounds, but not much.
RPG2's use the same firing pin as the RPG7, and those are readily available on the surplus market... Aside from that, and some serious good welding and a little machine work, not much is needed.
Much testing will be done before my head goes near it. Hopefully I can get started on it in the next six months or so.