Brass instruments are named so, not because all of them are made from brass, but due to the nature and texture of the sound they produce. They work with close to the same principles as wind instruments except for a few modifications here and there.
Yes, Tennis Balls.... Take an old tennis ball and cut it in half with a utility knife. This makes a great little cup to put your soap in to clean brushes after a day of painting. It's easy to swirl around in and I find does a better job than using my palm. I learned this tip at a plein air painting workshop.