Here are a few modifications to the awesome D-Bot CoreXY I did so I can re-use the parts from my Prusa Original i3 Mk2. The only structural change is to the screw brackets. Everything is customizable using scad. I hope the variable names are self explanatory.
Edit 1/24/2019: Added diff file with my changes to the Marlin standard configuration for use with this setup. It was essential to correct the maximum current sent to each motor! My extruder motor was overheating, transferring that heat down its shaft, and making the filament gummy. This was causing jams where the filament enters the tubing.