I'd be glad to help Vincent.
My ideas come from working in broadcast and IT, I've seen some techs I respect a lot do some really cool stuff. Those guys can be hired to create sets for SF series imho.
As I'm usually on a work budget, or have the connections to 2nd hand sellers for a DIY setup (using hardware leftovers from server room upgrades) in Belgium, I can't help you much with finding the right market. Try checking with local datacenters, broadcasters (often radio stations use smaller racks) or broadcast/DJ shops.
I can however try to give you a better idea of the components and working I have in mind. When I move to a house with a bigger work/play area, this is what I'm going for.
Working with servers, and designing server data rooms and cable plans, fueled my love for rack cabinets. It's like all the fun you have in clean cable and airflow routing inside a PC case, but on a much larger scale.
Some rack 101:
19" server racks come in all height sizes, width is a bit larger then 19" to leave room for cable management. Rackspace is usually divided in units. A full height rack would be about 40U (70"). A regular desktop PC lying in a shelf/cradle would be 3U. So you'd want a half or quarter size rack.
Depending on how you want to work with it, I'd leave 4u for the PC + airflow / cooling solution.
You can leave some more spare U's to fit:
- network switch 1u
- shelf for a router, control switches and dials 2u
- faceplate with holes and brush where your cables can be neatly routed through 1u
- patchbay, where you can link network cabling (eg labeled "Corner PC", "game console") and video cabling, port through rear connectors (usb, audio, ) etc 2u
That's a total of 10u.
Some examples of pre-made racks, you can get good deals on 2nd hand ones:
6U:
Another design:

*edit* looks ugly like this, but with the right paint job it can look exactly like a LRM rack

Side panels can be removed for side-to-side airflow routing.
Flightcase design, very portable:
DIY Home editing studio design, with some retro soundproofing:
Open cabinet (same principle as the top one, with side panels removed, full height):
I was thinking about this last model (not this large though). You can fit this open cabinet inside a larger frame. This larger frame is worked into your current wooden frame where you are planning to make the trap door. On the bottom of the larger frame you can add hydraulics (see bottom of this post), so you can lift the cabinet out of its frame. In the side of the frame you add flexible wires and your airflow solution. As an interim solution, you can just access everything from the front and forget about hydraulics, the PC can be accessed with a slide (see below).
Cabling example:


As you see in the picture above, in this rack design there is a lot of room between the front of the rack and the place where the device front/rear is. This is where you can go nuts on nifty cable management.
My tip: Put the cables in large flexi tubings (the ones resembling a throat, with ribbles). This way they can move along when your rack slides upwards. Also don't forget to leave a part of the cable freely hanging, as long as your PC is deep. This way you can pull out the PC without disconnecting cables.
Now on to the PC.
Usually a rackmountable PC looks somewhat like this:

The front can have various hot-swap hard drive bays, an optical drive bay, air intakes with washable filters...
Many pro cases (HP, Dell, Supermicro) have (optional) slide systems so you can slide it out of the rack without having to unplug it. Just lift the upper cover off, and you can check internals or serial numbers while it's still running. It work like this:

It's a bit of a fuzzy picture, but as you may notice this PC "floats" above the ground due to its sliding rails, attached to the side. This server is very deep and looks really heavy, still the slide holds it perfectly. Don't worry, just see that you get a sturdy rack. The DIY wood home studio rack might buckle under the stress.
Many data centers sell these cases as e-waste, because they buy complete new systems, often with entirely different sliding systems. Or look for a failing business sale, most curators don't know much about what these things are worth. You may get lucky and get a rack with PC, slide and some other components at a bargain.
The casing may look a bit boring for you. You can swap out the side and top panels for plexiglass, imagine something like this:

I wonder what the builder of this was thinking when he added a floppy drive though. Or is it a CF slot?
For the hydraulics to lift this out of its frame, you can scavenge parts from a hydraulic hand lift, often used in orderpicking warehouses, workshops or data centers. An example:

This one works with a foot pump, the "bike brake" is the release lever. You can swap it out for some electronic hydraulic engine if you prefer.
All of these are just "out of the box ideas" (look I made a word play there, haha). I can't really find proper pics of this kind of setup. It's one step further from case modding, but I think that's where you are at now: deskmodding
Hope this stirred up some ideas, and this isn't too far fetched.
Many of these ideas can be implemented on their own, just using a rack with proper cable management and a patchbay can relieve a lot of your cabling issues.
Edited by DeKamme, 28 June 2012 - 03:15 PM.