I did more on this last night than I thought I would. I found the bag of diodes, bent the positive leg of each one into a loop, and soldered up half the keeb minus the thumb cluster (wasn't sure yet which way I wanted the switches to go (they have to be sideways)). Then I started playing around with rainbow ribbon cable to see how that might go.
I'm going to try to get a better picture of the pre-solder diode loops for when I finish filling out the instructions.
None of the wire is soldered yet, just doing a dry fit.