Plus one to this. There are alot of project threads you can check out. I'm sure there is someone who can give you a blueprint or just simple directions for help.
I recommend atleast 1/2" wood. 3/4" wood is closer to .66" these days. Pine is a good material because its very cheap and usually the high end pine has good accoustics (deadening) and uniformity of grain (large soft grain and small knots if any). You can stain it to toughen the surface after sanding it to about 220 to 320, going the direction of the wood.
If I was to build a mid tower, I would buy the cheapest mid tower that newegg sells, some of them are in the $20.00 shipped range. Then I would cut the motherboard tray and rear IO paneling as well as expansion slot and power supply metal out, possibly the floor of the case up to the power supply as well. This would then be mounted into the wood chassis. This will save you a lot of effort because your motherboard will be mounted to a metal tray along with all your slots and your power supply so everything is grounded properly and fits together nicely.
If you are going for a particular small form factor, pick the chassis that has the shape you want, remove the metal skin panels and the front plate and then build a wood box for that to sit inside of. Thats what I have done in my latest project. I took an Elite 120 for $20.00 after rebate and then cut most of the metal out (hole in motherboard tray, removed the front components, removed the HD cage, removed the metal below the hd cage and mounted the radiator to blow down. The 5.25 remains but I don't have an optical drive so the front of the wood doesn't have any visible 5.25 slot. I have the 3.5" HDD in the 5.25 with an adapter.
With this setup, I actually don't need any input fans because I have a large vented hole on either side, one for the GPU, and one for the rest of the system. Power supply upside down provides an exhaust and the radiator exhausts down into the floor (hole through the wood).
It passed 27 hours of prime with a max temp of 65*C so it runs quite nice.
I will probably put atleast 1 or 2 server 92mm San Ace fans in to provide ram and VRM cooling once I have the case finally to my liking, still working on the metal grills to cover the vents.
Another idea would be to buy an open air test bench setup (basically a motherboard and power supply mounting system and nothing else) and then build a wood cover to put over it with fans and what not, so if you want to do some benchmarking take the wood box off the top, otherwise you can keep it safe and secure inside the wood. Some elegant router work could make it very pretty.
As far as switches go, I recommend the MNPC switch kit. Its worth the money. If you must go on the cheap, cut the switch plate off of a sturdy metal case and mount it to the wood, but its going to be ugly.
Dual22mm:
http://www.mnpctech.com/Bulgin-Anti-Vandal-Switch-Plate.html
1x22mm 1x16mm
http://www.mnpctech.com/Delrin-Bulgin-Vandal-Switch-Mounting-Plate_16mm-22mm.html You can buy one with a 22mm one and a 16mm one, or one with both 22mm. You can buy switches that light up with LEDS, so if you want a HD activity LED you could have your reset be that one and if you want a Power LED make that your power switch.
They are cheaper here:
http://www.performance-pcs.com/cata...ch_in_description=1&keyword=mnpc+vandal+plate