Thank you! I tried to do the keying method for lining up the joints and it didn't work to well for me, so I ended up just sanding them off and using super glue and doing it by hand. As for finishing, I sanded my parts down some first a bit, not enough to break through the skin and details, but enough to lower the lines down a bit. Next I'll superglue the components together and back the seams with a plastic epoxy. It typically dries to touch in 30 minutes. After that dries I will use bondo spot and glazing putty, it's a one part putty that air dries within about 10 minutes and sands like powder. Sand it using a medium grit sandpaper (240ish grit) down until it where you like it leaving a few pits here and there for weathering detail. Then, I'll rinse it off and let it dry. Next I paint it with a sandable fillable primer. Spray like 2 or 3 coats on it and let it dry. Next I'll wet sand it with 800 then 2000 grit sand paper and its ready for final paint. I use a respirator when applying and sanding the spot putty because its just as nasty as regular bondo.
I'm glad to hear you don't have to reprint your parts. I 100% recommend backing your seams with some epoxy. None of my parts failed or broke on my seamlines. They only stress fractured on the prints structure.