@rcarlyle Yes, this small stainless steel tube, thus cooled, opens up a whole bunch of possibilities, which I am currently developing, and which I hope to be able to offer after Kickstarter. 1 - The volume of the Hot End can be divided by 5, and the weight reduced by 3, by directly integrating a miniature nozzle at the bottom of the tube. It is the tube+nozzle assembly that would become interchangeable, rather than the nozzle only. 2 - These miniaturized hot-ends make it possible to have a very light extrusion head, of the Direct/remote type, with two or four independent extrusion channels, but with a single drive motor, in the Flystruder position. I have already made a single-track version, which works extremely well. Delta printers have great qualities, but they were generally limited by their single-channel Bowden tube. With 4 printable materials, you can imagine the possibilities!