It's been too long coming for all sorts of perfectly valid reasons but at last I have the completed PCB design for the Maxi-Controller.
The Arduino I/O processor is mounted on the PCB, behind the display and this means that all the connections to the various controls can be printed as tracks, considerably reducing the amount of wiring required. Of course it makes the board a lot more complicated and that is one of the reasons it's taken a while to get it right.
Most of the problems aren't, in fact, anything to do with the PCB circuitry. Mainly it's a case of getting all the components to fit without getting in each other's way and, notably, ensuring that the few cables that are required don't snag on other parts of the board.
For example, it has proved necessary to move the two vertical columns of pushbutton switches about 4mm further away from the display so that the display's HDMI cable can be fitted. Similarly, we had to move switch multiplexer 0 from the top of the board down to the bottom in order to make room for the USB cable to the Arduino.
The good news is that in fixing the maxi-controller board layout we have now solved pretty well all of the problems we are likely to come across on the mini-controller PCB. Once the maxi board is into fab we can get started on the mini PCB and should have it done in a few days (famous last words!).
Here are a few more views of the PCB