The default Printrbot LC/+ carriage will not comfortably fit the E3D hotend. Additionally, the shorter length of the E3D hotend causes problems in the Z axis, especially if using one of the many Z stabilizer upgrades. This carriage is designed as a bolt-on replacement for part of the stock Printrbot X carriage. It allows the hotend to be mounted lower and lets the nozzle reach the print bed even if using Z axis upgrades! Additionally, this mount has been made to be smaller and lighter than the stock part, and includes a built-in guide for wires. Additional holes have been left for a future fan mount (coming soon!). Fits the E3D hotend and any other standard groove-mount hotends. The 10mm hole on the top is made to fit push-to-fit penumatic fittings for a bowden tube. If requested, I'll upload additional sizes. Update 4/3/14: A version for the v5 Bowden E3D hotend (with threaded top) has been uploaded for additional compatibility. Use the Factory Bowden .STL if you've purchased that version! Special shoutout to David and Sanjay at E3D, keep up the good work. :)Print the mount as is with support material. I recommend using 3 loops/perimeters with low-medium infill. File or dremel away the support material, especially in the groove-mount area. Be careful not to remove much part material, or your hotend will not sit perpendicular to the surface. Additional finishing may be required depending on printer quality. Unscrew the four screws holding the extruder mounting assembly on the Printrbot X carriage. Use the same screws and washers to attach the new part. It'll be a bit tricky getting the top two screws lined up since the washer overlaps on the fillet. It'll still fit though! Mount the E3D or similar groove-mount style hotend by pressing the hotend into the hole and screwing in two long #6 screws. The ones used on the Printrbot Wade's extruder work fine. Mount your pneumatic fitting as well, and check alignment with a piece of filament. Some misalignment is allowed, but less is better!