I stumbled upon these, and have found them handy for painting small circles. Just dip the ends in paint (and you can snip off the ends for different sizes), and carefully dab onto any surface for a perfectly round application that would be very hard to duplicate with a brush. Unfortunately, the human eye is VERY GOOD at detecting out-of-roundness! My HO-scale truck bed's tail-lights are an example. Pilot-figure eye-balls, instrument panel dials, and fuel-ports come to mind as possible uses.
