I do that too. One of my most popular colors is semi-gloss black. It is amazing for suspension parts, brackets and, air cleaners all kinds of other car related parts. I will tell people who want that color that if they can wait a couple of days, I'll combine it with another batch and save them a little money. It is WAY easier to do one batch of, let's say, 16 parts in semi-gloss black than two separate 8-piece batches.