After some research I see this idea was mentioned by Mike on the blog in 2011.
However I just thought of it today so I thought it might be worth mentioning again. I used to use small brushes to paint small fretwork holes and slots. It was always a mess and a real time-consuming pain. So today I tried a pipe cleaner on one of my projects. And boy do they work GREAT. They get right into very small slots and holes. Places where you can't get a small brush.
I found some "pipe cleaners" at Joann's in California ( they call them "stems"). But I'm sure you can find them in most craft stores. Probably even a Pipe and Tobacco store. At the craft store I purchased a pack of 25 for only $0.99.
I'll never go back to brushes for painting or staining intricate fretwork.