If you have a desk without a shelf that pulls out for your computer keyboard, you can easily make a shelf, and attach it to your current desk. Once you see how easy it is to do, you will want to get started right away.
Measure the distance between the sidewalls of the desk, or between the file cabinets. Measure the width, and cut this amount in half. The sliding shelf does not have to be as wide as the desk. Find the drawer slides you will use. This will be the length of the wood piece you need, minus the thickness of the drawer slide on each side.
Make marks on the file cabinet drawers, or the sides of the desk. To determine where the comfort level will be for the keyboard shelf, sit in the chair in front of the desk, and place your hands and arms in the position in which will be comfortable for you to type.
Attach the draw slide mounting to each side of the desk where you have made your marks. Make sure to attach the front of the guide at the edge desk front.
Attach the other part of the draw slide to the piece of laminate wood. Secure screws with the screwdriver on both sides of the laminate wood piece.
Place the shelf into the wall slides, and secure according to the directions for the particular draw slides you are using.
This is a very easy project that takes only about a half hour to complete. Use a laminate piece of wood for a smoother finish, and you will not need stains and other materials.