After building up and modifying some of MoonCactus' great XY blocks, I realized that although the design was spectacular functionally, it was about equally as challenging to assemble as the stock UM XY blocks. So while trying to maintain the major benefits of the original (integrated adjustability, low profile, removable without taking out the 8mm axes) I set out to redesign them - with improved assembly and accessibility. The result is the Reptar XY block, a strong, easy-to-print, easy to assemble, highly functional XY bushing block... which was designed almost in its entirety before I printed it in purple and green and embraced the fact that it looked like a dinosaur. ...Anyway, like I said, it offers some big usability improvements: The Main body (green part) snap-fits onto the bronze bushing and the 6mm rod, holding them captive - which means you can assemble most of it without any screwing, and then add screws later to make everything secure. All of the screws are accessible from the front side, including the tension adjustment screw. This is a very nice feature and makes assembly much more enjoyable The bronze bushing does not get deformed as you tighten things up The necessary non-printed parts per block: 3x #2 x 0.5" Torx Drive Plastite Screws (+1x when installing the limit switch spikes) (McMaster P/N: 99512A162) 2x #2 x 0.75" Torx Drive Plastite Screws (Mcmaster P/N: 96001A164) 2013.08.20 - v1.16 Update: I've uploaded the latest STL files, after printing several dozen of these and installing them on 3 machines. I now believe, however, that a combined XY block + tensioning mechanism is not necessarily the best path forward (see comments) and will be redesigning this in order to simplify it further. 2013.08.06 - v1.16 Changelog: Added small tabs to locate the bushings! 2013.07.31 - v1.15 Changelog: Changed the shape of the clamp jaw to get better clamping and a cleaner print. Parametric files only at the moment, I'll upload STLs when I get a little more testing in. 2013.07.30 - v1.14 Changelog: Updated switch trigger clearance. There will now need to be two separate parts for this, unfortunately. Uploading the longer one soon. Made some improvements to the tensioning mechanism as well as the clamping. Parametric files only at the moment, I'll upload STLs when I get a little more testing in.Print each piece at 0.1mm layers or thinner, no brim, no raft, no support! The main body (green in the photos) should be printed on it's back (with the axis of the 6mm rod semicylinder pointing upwards). The purple clamp body should have the axis of 6mm rod semicylinder parallel to the bed, with that face down. The print lines should be clear in my photo.