Instructibles user [Deathrogue] has come up with a simple and elegant way to label bottles for reuse. A patch of chalkboard paint can be applied in place of a label. This simple idea is actually fantastic for people that make tinctures, brew meads, beers, and wines, or apparently store m&ms and can’t tell what they are by looking.
All joking aside, this would be quite useful when doing long time activities like mead as mentioned above. Often you have a dark bottle and you add spices for the aging process. This would be a perfect way to keep all your different variations clearly labelled while you wait.