Blue Commodore 64
This is my workhorse. I do a lot of hardware hacking with it - replacing chips and other parts, hooking up experimental electronics projects - the works! Its screws are permanently removed so I can access the internals quickly when needed.
I painted it blue several years ago with Krylon Fusion spray paint which "bonds the paint to the plastic". As you can see, it does wear off over time (mainly on the corners where there is heavier wear and tear).