I'm getting a full tower that won't fit inside my desk and I've heard that putting your case on carpet can build static... I'd rather not put it on top of the desk itself. So I'm thinking about making a case mount using some wood to prop it up off the floor. Sound like a good idea? Or do they sell things like this?
Putting your case on carpet isnt going to build static, your case is grounded through your power supply so it isnt possible to build up any notable quantity of static between it and the ground.
Getting it off of carpet a bit can help reduce the dust its exposed to so that can be a good thing, if you just need a basic stand for your case to sit on go to home depot and get them to cut you an appropriate length piece of 2x8 or 2x12 depending on how wide your case is.
A few years ago I made a pc stand from parts I purchased at a hardware store. I got a 12 inch by 24 inch ready made shelf in an ebony finish. I added casters to the bottom of the shelf so I could move it easily. It is a 15 minute job that is very easy to do.
Later I made another one using two shelves, four 6 inch long chrome plated metal tubes, and casters. The four metal tubes between the two shelves raised the bottom of the pc about 12 inches above the ground. You could substitute 2x2 lumber for the metal tubes.
Highly recommended if you have a pc case with a bottom mounted pc drawing in air through the bottom of the case. Ventilation and airflow will be restricted if you place a pc with that configuration on a carpeted floor.