masking tape

This isn’t something groundbreaking or revolutionary, but it’s something that I have been doing when painting small pieces that easily roll away when bumped:

I use masking tape inside-out, tape it down on the sides for good measure, and then put the little bits upright in the way that I’m going to use them so they stay in place and I can paint them on both sides at the same time. Bonus points: I can just pick up the piece of paper I taped them to and set it aside to dry without any extra effort.