Building a computer offers plenty of options for the enthusiast. Clever builders can make their rigs as powerful and speedy as they want. But all that power and speed will be invisible if you stuff prime parts in a plain off-the-shelf case. The true mark of a custom computer builder is the ability to build a unique case from scratch. It's not as hard as it may seem at first: Any solid building material---metal, Plexiglas, stone or even wood---can be turned into a case if you allow the space for parts and ventilation. For a basic set-up, you will be creating a six-sided case, one of which will be a detachable access panel.
Measure out the dimensions you would like for your case. Remember everything you need to fit inside: a motherboard, processor, PCI cards, power supply, disk drives and ventilation or cooling systems. Cut out each panel of the material you're using, checking to make sure the opposite sides match exactly.
Place your individual parts where you would like them on the panelling. Remember every mount will be located on the side opposite your access panel. Use a felt tip pen to mark where the screw ports, USB or other plugs and disk drives will connect or penetrate through the panel. Be exact and place your parts back against the marks to make sure they are in the proper place. Use your 3/8" drill to make screw mounts. Make disk drive, power supply, and all other ports with your carbide cutter.
Install mounting bracket frames for your hard drive and disk drive. Screw these into the case on the side opposite your access panel.
Assemble your panelling. Rivet the permanent sides together and drill screw mounts for the detachable access panel.
Put any finishing touches on your case. Spray the exterior surface with paint primer. Paint your desired design onto the case, then finish the design with enamel for a glossy, mirror-like finish.
For a truly unique case, use existing items like a television or a jukebox as a starting point. "Measure twice and cut once" is doubly true when dealing with electronics. In fact, if you don't buy your parts before you build your case, cut out foam blocks in the correct proportions for items like the power supply and disk drive to gain the correct measurements. Leave some extra room in your case to accommodate all the cables that you will need to run through the case.
Don't forget to drill holes for air ventilation. If using a metal case, be sure to watch for any small pieces of metal that could cause short circuits.