I've built fourteen 1/350 scale model warships built with 3D-printed parts in the past two years, ten of which were entirely 3D-printed (aside from brass gun barrels). A couple had issues with incomplete hardening/curing of the resin, resulting in liquid leaking from them, but these parts were washed in 91% isopropyl alcohol and that solved the problem. The leaking was, fortunately, from inside the parts (they were superstructure sections) and did not distort the exteriors. For 3D-printed hulls and brass photoetch I've just used Tamiya light gray spray primer, which fortunately was a close match to the final color I wanted for these parts when painted.