What Pat said. If you're only going to do a few it's probably easiest to spray paint them. You can make a dip tube out of copper or pvc pipe. If you use a small diameter it doesn't take much paint. The level in the tube drops drastically with each dip so you'll need to add paint often. Most dip tube have a large diameter reservoir at the top so you can dip a lot of arrows without needing to fill the tube often, but for only a few arrows I'd just make a straight tube and fill as necessary. Be sure your cresting paint is compatible with the dipping paint. Basically, don't put lacquer over anything but lacquer. It'll eat up most paints. Conversely, with lacquer on first, you can crest with almost anything, including markers.