This is not a computer made of plywood, but a computer made with plywood. Sorry for the low quailty pictures.
Step 1: Parts and tools
A small piece of 1/4" plywood (roughly 2'x2.5')
Video Card (if supported by motherboard)
Floppy drive (optional)
Required IDE cables
Pwr and Reset Switches
Pwr and HDD LEDs
Sound card (if not on motherboard)
USB card (optional)
Processor (if not on motherboard)
Step 2: Attach motherboard and cards
For the mother board, the best way to place it is to have the longest edge of it on the longest edge of your plywood. When you are happy use three or four screws to hold it in place. Then attach the RAM and any cards to it along with the processor if it wasn't already attahced.
Step 3: Power!
For best placement of the power supply, I suggest putting it behind the motherboard. Then tack it down with some glue.
Step 4: HDD and CD
The CD drive can be placed anywhere you want it on the plywood. For entertainment purposes, I took the cover off of mine. This can also be held down with glue. The HDD can also be placed anywhere. I just left the harddrive free so I can use it on other computers I get that don't have harddrives.
Step 5: Lights, Switches, internal sound and floppy
The lights and switches can be mounted or just left free. the speaker can be the same way. The floppy dirve, if desired, can be mounted, with glue, in any space left on the board. The pins where the lights and switches go should be labled on the motherboard next to the pins