We spent months on getting the LED holes in the front panel to the right size. The problem is (again, had this with other PiDPs) that you specify a, say 5.1mm drill hole. Depending on the wear on the router bit used at the PCB manufacturer, you get 5.05-5.15 holes on the boards they send back. But we wanted the lamps to really sit neat and flush in the panel. So the only solution was to order about a dozen test samples to test what would be pretty-but-not-excessively-fidgety...
Now the fit is not very fidgety anymore, but in some of the early prototypes I had no fun. It's one reason for that odd Ottopanel: it has slightly wider LED holes, so the actual front panel on top finds the LEDs already pre-aligned.
Builder feedback was also very useful. I always used to put all the switches on the PCB, then put on the front panel, flip over and solder up.
But doing the switches row-by-row is easier. Building Instructions updated soon, I just made the photos to illustrate that new process today (on my first 'production' PiDP-1, so far I only had my prototypes to work on!).
Kind regards,
Oscar.