@ Dan

I plan to use general purpose aluminium alloy (5005) flat sheet - with the standard mill finish. My local supplier will cut to size.

I will centre punch the button locations and use a standard 16mmm metal drillbit in a bench drill to cut the holes for the buttons.

I will use a finer drillbit to drill a row of holes along the fader slots and finish with a jigsaw and file.


@ Bachus

There are several vendors of MIDI encoders and decoders.

I have used some HWCE2x encoders from Midi Gadgets Boutique. These worked well.
http://midiboutique.com/index.php?route=common/home

This time I might use some MIDI encoder + extension boards from Midi-Hardware, e.g. their MBBS plus a couple of BBS-1Ks for the extra buttons and a couple of daisy chained POT12s for the faders.
http://www.midi-hardware.com/index.html

I'm not using lit buttons and MIDI decoders on this first 'experimental' version of the Control Surface because that would more than double the cost of the prototype