I lucked into finding a great fridge. It's essentially a single exterior door and has a dorm-fridge style freezer section inside, so it's just an insulated box with coils on the back. It is light, and once emptied out it held five cornies.
Because it's a fridge, I won't need temp controllers (I am testing it now). It also has the benefit of a stand-up freezer in that it's a single door, so my taps are up and out of reach of my child, and at a nice eye level. I also installed a latch on the side I can lock to keep him out.
Anyway, I hauled it home (light enough for me to pick up and move by myself). I cleaned it out and it sat around waiting for me to get the parts.
My brother came to visit and tore out the inside of the door and replaced it with a pebble-board panel (but reversed so it's smooth). He also built a smooth flat solid shelf that is well supported for the kegs.
I got an 8-faucet drip tray (only using six of the holes) that mounts with the shanks. I put on five stainless steel Perlick forward-sealing faucets and one stout faucet. I can only put five kegs inside, but I figured I might not always have a stout but should always have five kegs. In the two remaining holes I may one day add shanks and faucets and dedicate one to soda (for my son) and one to sour beers, along with kegs that get painted and labeled for that use only (for either, since I wouldn't mingle soda or sours with the rest).
I ran gas lines out the back and around into a closet where the tanks can be stored safely. I have CO2 hooked up, but need to go pick up a beer-gas tank. The beer-gas runs in a simple 5/16 ID line and has a connector inside, so it will be controlled just by it's primary regulator. The CO2 has a line from it's primary into the fridge where it feeds a series of five secondary regulators (Micromatic's high-end models) that are chained to run declining pressures with beautiful dial knobs and gauges. Each of these has a shutoff with a check valve to protect it, and runs to a gas connector.
The connectors in this whole thing, both beer and gas, are done with flare fittings so I can change out taps for commercial or specialty kegs if needed. I also set each one up with 48" beer lines (3/16" ID) for each faucet, and since these also have flare connectors, I made a set of extensions. I made three 6", three 12", and four 24" extensions so if I run a higher carb beer at a higher pressure I can balance the system with longer hose extensions and dial it down to within six inches.
Inside each shank has an elbowed tailpiece so the beer lines hang straight down and won't kink, and the shank and faucet are the highest point. When not connected they hang just shy of the bottom of the fridge and there is plenty of room for the door to close.
The drip tray has a threaded drain down-tube that I have just capped for now, so I can uncap it to flush it out if needed.
Parts laid out:
If anyone wants more detail, I'd be happy to share. I learned a lot from building previous systems, and have taken classes with Micromatic (I was trained as a pro-brewer, I'm just making more money at my not-brewing job right now). I have to say that the beautiful spreadsheet published on this site in the software forum is a great tool for balancing.
One thing I don't know is if or how to balance a line that's using a beer-gas mix to push to a stout faucet (75/25 mix, 32 psi, 40F).