I am looking to Fabricate my own computer case, which materials do you guys use and is there anything I need to keep in mind?
Zinc steel available at the Home Depot for 4.88 for a 12x24 sheet. 24 gauge. I would have used aluminum but it was too much. Now that I have done it in steel I might redo it. Depends on how you plan on using the case, exposed or hidden, cooling, etc. Mine was originally to be in the dash so only the front was showing, but that changed, so I had to do a better job on the front 1/3 of the case.
I originally cut up an old ATX case I had, looked okay but the textured paint starting chipping where I bent it (in a vice and with a hammer on an anvil, Jesse James I am not) so I bought a sheet at Home Depot.
People use: Aluminum, steel, plexiglass, cardboard, MDF, etc.
I got some Al sheet from Ace 24x30x.025" for ~$13 a sheet. I'm going to use .50" Al angle iron for the frame.
You need to determine where it is going to be first. Then determine heat and airflow. You'll probably then want to decide cost vs cooling.
You could get a sheet of 24x30x.5" MDF for $5. It's heavy, dense and non-heat-conductive, so you probably won't be able to hear the PC, but it'll heat up faster (so you'll need one or more fans.
Pretty much, though, what is easiest for you to work with? For me, metal and fiberglass are a PITA. Wood, I enjoy working with. Plastic/Plexi never had a chance to work with.