My 3D printer did a good job printing the parts, so I'm only going to fill some areas with Bondo (for plastic) and smooth others before applying the primer. For the finish job, I'm following in the footsteps of Tommy. The materials for this part are:
Automotive 'Plastic' Bondo
Sandpaper (220, 400, 600)
Rustoleum Automotive Primer - Grey
Rustoleum Flat Black
Rustoleum Metallic Aluminum (for front of barrel)
Tamiya Weathering Kit Master #D (Burnt blue, Burnt red, Oil stain)
Extra Tamiya Applicators (kit comes with one, will need at least three). I plan on going to the local make-up isle for Tommy's purple and possibly extra applicators.