I used a perforated breadboard to hold most of the components and control circuits, and mounted it with a couple of aluminum brackets made from scrap.
The lower-right picture shows the placement of the RCA phono plugs on the back panel. These are used for the T/R keylines to and from the amplifier.
The pink muffin fan on the rear panel draws air from holes drilled into the floor of the amp (not drilled yet when this picture was taken). It's mounted to blow the air out the rear.
This particular fan already had a speed control built into the cable, saving me from having to make one for it. Still, I wired this fan in series with the one that blows air across the cavity, slowing them both down for quieter operation.