Got an extra RGB LED and thinking where to put it? Why not to make a fancy RGB blinky that could emit various nice RGB patterns.
It doesn’t require many parts and can be soldered by anyone who is not afraid of soldering iron. RGB blinky is also known as Lux Spectralis and can be purchased as a kit, but you can also build it from scratch as all necessary files are provided. Atiny13 program already has a bunch preprogrammed light modes that can be changed with push button. Fun to build and even more fun to play with.