I have tried both before and after painting methods. When painting first, paint has to be scraped, or the area masked. When assembling first, masking has to be done for each color......to me that's six of one, half dozen of the other. I complete the build, and mask and paint after assembly, unless there is a requirement for interior painting, that has to be done before assembly, as in the junkbuild I did in the Sci Fi forum. I don't have any problem with masking, and it isn't any more annoying for me than scraping off paint before gluing. I just prefer painting after assembly is done.