With some feedback from an expert, I’m now armed with the knowledge that I can easily daisy-chain six of the aforementioned motion control boards to drive each of the motors in the robot arm. And my old USB-to-I2C board actually has a number of general purpose IOs, making it easy to engage/disengage the brakes on the larger motors. Getting a lot closer…

My barber & I got a lot closer, too, recently. This is pretty much the shortest my hair has ever been. Period.