Building a 3D printed keyboard seemed like a fun idea. I made one, based on Michael John's Dactyl-cc keyboard. I've been using a Kinesis Advantage 2 for many years, so this split keyboard seemed like it wouldn't be much an adjustment. It's really nice to use - my only complaint is that its very light and easy to slide on a desk.
Here are the bits that went into it:
Printing the kyecaps was a bit more challenging that I thought - there are different physical shapes for different keys, and you have to be careful to keep them organized correctly. This was complicated by my choice to keep them blank. (I'm a touch typist, so I never look at the keys anyway)
Wiring was tedious. I got good at stripping the wire mid-way through to wire the columns. Using stripped wires for the rows saved a lot of time. For a few columns, I just wrapped the insulated wires around the keyswitch leads, and applied the soldering iron to melt away the plastic and apply solder. This did work, but smelled a little too cancerous for my tastes, so I decided to play it safe and spend the extra time stripping sections of wire.
Notable learnings and design choices: