I designed all the electronics to be mounted to the top of the electronics box so that the bottom panel could easily be removed if the electronics needed to be troubleshooted. The Arduino Mega, stepper motor controller, prototype board, and instrument wheel are all pressed into the top of the box using the mounts. A few lasercut parts slide over the boards as shown in the images above. These parts then press into the holes in the top of the box. 

All the electrical components shown in the diagram are soldered to the prototype board: transistors for controlling the laser diode modules, resistors for the photoresistor circuit, pins for front panel components. There is a lot of soldering work here so I'd like to some day make a PCB for the upright laser harp.