I have set up a custom modified Ender 3 running Klipper with three SKR Mini E3 V3 controller boards that has a 4->1 mixing hotend as well as an additional carriage with another hotend. This allows the printer to handle printing CMYK colors through the mixing hotend as well as support or other material through the additional hotend.
Here is a link to the Klipper config
I am learning CAD and have a functional knowledge of Fusion 360. I have created a few things, including:
External GPU enclosure
Fractal Vise
Replacement door handle for a sliding glass door
Replacement arm rest for an office chair