I was considering using a vendor that sells us products here at work (not bicycle frames). I doubt they have any experience with bike frames. I didn't think about masking the BB & head tubes. I was thinking that I could install screws in all of the braze-ons & then back them out when finished. The other complication is the couplers. These are stainless steel & would need to be masked. I assume that the masking material would have to withstand the baking process.
Maybe this is a foolish idea. I don't want our bike frame to be their learning curve. As I understand it, powder coating is less process sensitive than wet paint. They just charge the metal & powder opposite & spray the powder toward the metal. Some powder electrostically sticks to the metal, the rest falls to the floor. However, because the charge density is higher at the edges than in mid-surface, the powder tends to be thicker near edges. I also emailed Co-Motion for a quote on repainting the bike. It's really not in that bad of shape, just has a few scratches.