This one is roughly in the category of “Why would you do that?” but Unprecedented has gone ahead and done it anyway. He’s taken a few 3D printed parts and some tubing and created a water cooling system for the Raspberry Pi. You can read how he did it over on Instructables and you can see more in the video below. Obviously, doing this yourself requires a lot of guts and know-how and it’s not recommended unless you really know what you’re doing.