Select a desk frame the appropriate size for the space in which you intend to place the desk. You can find basic desk frames online or at your local furniture store. You may also choose to use an old desk you already own by removing the top and painting or staining the base to look like new.
Measure the width and depth of your desk frame and decide how much larger you want the desk top to be. Since glass is very heavy, it is unwise to make the top more than a few inches longer or wider than the desk frame because the desk frame might not be able to support it.
Have the professionals at your local home improvement store cut a sheet of tempered glass to the dimensions you determined earlier. The thickness of the glass you select is up to you but keep in mind that, while thicker glass may be more durable, it will also be heavier. A glass thickness between 3/4 inch and 1 1/2 inches should be sufficient.
Clean both sides of the glass thoroughly with glass cleaner and a paper towel. If the cut edges of the glass are rough, it's advisable to smooth them with fine sandpaper prior to cleaning the glass.
Apply clear adhesive rubber bumpers to the top edges of the desk frame. The number of bumpers will depend on the size of the desk, but at a minimum, you should place one bumper at each end and in each corner. Additional bumpers may be placed every 6 inches along the top edges of the desk frame.
Set the sheet of tempered glass down on top of the desk frame so it rests on the rubber bumpers. Adjust the position of the glass so the desk frame is centered below it. You may require help to lift and move the glass for this step.
Clean the surface of the glass once more with glass cleaner to remove any fingerprints you may have left during the assembly.