This is a thing in progress b/c of the way the hot ends are attached. This is a generic, minimalist, extremely light, dual-head-ready, two-part only, quick head mount replacement for the ultimaker. I am using it most of the time in place of the stock mount. It can be used like this but there is also some work/upload to be done for a better attachment to the hot ends (see the instruction for more). See, eg. the specific mount for the E3D on the last picture (http://www.thingiverse.com/thing:159987). Should work with almost any 12mm OD bushing/bearing long enough. Once the two parts are assembled together (4 screws) it can be mounted/disassembled in about 1 minute: Just swap it with my reciprocal stock-compatible mount: http://www.thingiverse.com/thing:137847 It also has provision for a dual head, even though I never tried so far. For now there is nothing beyond the couplign screws to attach a fan, I am mostly using a separate 120mm fan to blow on my plate (and it works quite well). Check the instructions for more.Best printed in Nylon, or may be ABS, unless your head is well cooled in which case PLA is OK (I used both PLA and Nylon -- Nylon is a bit elastic, did not notice any impact on the quality though, may be it is even better?!) I had it working quite well with miscellaneous hot end. The thing is in progress as I test different variations of the mount, as you can see: there is a dedicated E3D hot end mount (last picture), but I sometimes just clamp the push-fit connector itself (see it on the E3D also). Grabbing the push-fit is certaily not the best thing to do, because it makes the whole head higher. But it just works quickly for almost any kind of head I want to try. WIth a low-profile hot end and/or dedicated attachment, I get a total height which is smaller than the stock one (~1cm shorter), hence less wobble at the nozzle due to the linear bearings. I will post about it another day.