It was a pretty straightforward task to assemble the bits into a functioning 4×4 nixie matrix. The tubes are mounted on spray painted black MDF with the PWM driver mounted on the back. They are each held in place with a small square of double sided foam tape. Wires soldered on the back to the tubes create a small nest and will be more neatly managed of the bigger version. I programmed an Arduino with the Adafruit pwmtest example and it all works fine. In fact, it works much better than I expected and I think I’m ready to go full scale, with no real modifications. All seems too easy.
I did a measurement of power consumption and the 4×4 uses a power of 1.8W, so will need about 15W for going full scale. Not too bad really for 128 tubes.