This is a new kind of cooling system for hot-ends, based on a little air pump.The ring is designed for a ORD Bot Hadron, but can be adapted for other 3D printers.Print:You need:I didn't make tests, as I'm waiting for my new hot-end (sold the previous one with my first 3D printer, a nice Prusa, replaced by a ORD Bot Hadron), but I tried by maintaining the tube from the air pump by hand, and it seems to work fine.My pump says it can reach 100l/min when the tube is 45cm below the surface of the water. Don't know yet if it is enough for printing at high speed. I plan to design a custom centrifugal pump, like this cute one: http://www.thingiverse.com/thing:4839. Another way to go is to use a little compressor, but this will need a pressure regulator!The ring has 3 holes for leds.