I just wrapped up assembling the third prototype. It was a great experience to build 3 completely separate units, I learned a good amount from each build, and made tweaks along the way. I uploaded my current firmware and so far everything seems to be working as expected.

Some of the major changes I included in the newer prototypes include:

• Using shorter potentiometers and redesigning the indicator knobs
• notching the upper PCB to make clearance for the MIDI connector
• Swapping out any SMD components on the upper board for thru-hole components
• Removing the SD card slot and RAM chip
• Upgrading the 30-pin connector to a flex connector
• Adjusting the bosses and ribs on the enclosure to be more robust 
• Adjusting the 2 pots to the right of the left-most buttons (the original design was slightly misaligned)
• Optimizing my resin 3D printing orientation to reduce the number of supports and make post-processing easier
• Discovering a more efficient way of post-processing the 3D prints to get a glossy finish (220 grit -> wet 2000 grit -> clear acrylic does the trick)

Anyway, here are some photos below. You can see the difference between the original design and the updated one, I managed to lose about 0.5" of height, which is great. Next steps are to resolve some firmware bugs and then I plan to send them out to friends to get some feedback!