Migrated to:
https://www.printables.com/model/541809-creality-ender-5-and-pro-extruder-re-mount-updated
UPDATED: I've re-created this in Fusion 360, and adjusted holes, modeled in screw-threads. Should be more robust, less prone to cracking or slipping.
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I made this mount so I could shorten my bowden tube, which in turn lets me reduce the retraction during prints to 5-6mm with PETG, helping to reduce stringing
You'll need a stepper motor extension cable, and a PTFE bowden tube kit with M6 and M10 connectors (same size as the Ender 5 I have here uses).
I recommend you look for a kit that has a tube cutter, so you can get a really straight end on your tube (though you can install this mod without removing your bowden tube from the hot-end; if you take this approach, trim excess at the extruder end).
You'll also need a couple screws and matching V-slot T-nuts to secure the mount to the printer. I _think_ I used M5x8mm button-head socket screws.
You _will not_ have to tap any metal.
I used the PTFE tubing from the bowden kit to act as a filament guide tube from the mounted filament guide to the connector at the back of the extruder. I used my new flexibility to mount the filament spool holder on the left side of the machine sort-of-flush with the left side (not really intruding into the cube frame, you understand), which better suited my space and accessibility needs. One could probably make a case for mounting it in back and flush, too.
It can be a little finicky to add tightly curled filament (from the last stuff on a spool) and get it into the extruder properly. I usually work it up to the extruder inlet (there's enough finger space to fiddle with it a little) and let the extruder motor take it in (hotend will have to be >170C for this to be allowed by the control panel) then once it's properly in the bowden tube, I release the tension and push it up to the hotend from the spool side.