I have built myself a keyboard, and am sadly proud of it.
I didn't do any of the tricky electronics or software - I used a pre-existing PCB for the "Phantom" design, and existing firmware on an existing microcontroller board. I did solder it up myself. I did minorly tweak the design of the metal keyboard plate (editing .dxf files! Woo!) before sending it to a laser-cutting company.
I did do the physical assembly. It was the first time I'd spray-painted metal - it does produce a lovely finish. It was the first time I'd attempted woodwork in about twenty years. I am still absolutely useless at it. The result, at best, might be described as having rustic charm. It works, no-one's going to mistake it for a professionally constructed device, and I'm still proud of it.
If you want to know more, I put up notes on github.