The design shows in the last step wasn't very good. There were too many wires running between the stack of boards on my hand and from the stack to the audio/video effect bus on my forearm. I was spending so much time dealing with the mess of wires I could never get to designing the audio/video effects. The solution was to abandon that iteration of the project and design a new one. I put the VGA generator, sample-and-hold, and light detector circuits onto a single PCB and dropped the idea of swappable effect modules. The LED display board is no longer part of the project.