This is the smaller version with several refinements to comply with the Supercon 8 Add-on Contest. It looks better in the smaller form factor, and I removed some experimental stuff from the previous version.

Here it is on the bench with testing underway:

One of the "improvements" I made has to do with pin allocation on the I2C GPIO Expander, as it related to the row wiring and also the LEDs. I think I made a mistake that is still functional, but changed polarities on the row drive wires. The newest version works, but I need to make some code tweaks to get it working as smoothly as the first version. More to come soon!