i got a cheap cabinet from walmart:
Purchase the Mainstays Storage Cabinet, Alder at an always low price from Walmart.com. Save money. Live better.
the back was just cardboard, so i was able to easily cut holes in to route lines. then i used a hole saw to knock out some holes in the side wood for additional equipment routing.
finally i took a spare shelf that came with it, and used it to mount my controls and such to. then mounted it at an angle inside the cabinet.
you can see the shelf here being measured for mounting and having the holes drilled for running cable:
here is the finished product. this is just the top half. the bottom half will be covertly housing a saltwater mixing station, but that's not finished yet.
everything is held on the board with wire tires. it was the easiest way to securely mount them. behind that panel is a freakin' rat's nest of wires. but it doesn't matter, because no one can see it.