So much sanding and filler primer ;) I wasn't the only one to find the tabs for alignment didn't fit - I had to either grind down or cut off the tabs, or grind out the hole. Really slowed the process down. I also joined a few pieces in Tinkercad and changed print alignment. Given that I printed this over a long period of time, it's probably a mix of ABS, PLA and PETG.
I painted it while the gun was in 3 main pieces - the main gun (with stock, grip, magwell, shroud), with the top barrel and launcher separate parts from the main body. This is so I could get into the nooks and crannies. I then glued the pieces together afterwards (in Tinkercad I'd made a hole for the top barrel to slot into).
Painted almost entirely with an airbrush. After an undercoat of flat black;
* Satin black for pump grip
* Mix of flat black and gun metal for the grip, barrel, top of Thompson and stock
* Olive drab for the shroud, counter and mag well
* Gloss black and red plus clear gloss for the counter