If you have an old flatbed scanner/printer that you are no longer using, you can take that old piece of equipment and convert it into light box instead of throwing it out or recycling it. Light boxes are used for a couple of applications. Photographers use them to evaluate slides and negatives. Artists also use light boxes when they need to stencil or trace a specific pattern. Converting the scanner to a light box is not that difficult, especially since you already have a cabinet to work with.
Unplug your scanner/printer and let it cool down if you have been using it. Remove the paper trays and any ink cartridges from the scanner/printer.
Disassemble the scanner/printer by first removing the lid. In some models the lid may simply lift up and off, others may require brackets to be removed.
Remove all external screws and open up the scanner/printer's casing.
Remove all the internal components form the scanner/printer until you are left with only the casing intact. The internal components will likely be held with a combination of screws or other nuts/bolts. You will only need to have the casing intact at the end.
Install a fluorescent light fixture in the bottom of the scanner/printer compartment. Choose a light fixture that has a "line switch" to turn the power on and off, as opposed to having the switch on the actual fixture itself.
Place a piece of wax or white parchment paper on the inside of the glass platen. You want the light that is coming from the internal light fixture to be dispersed. You can also replace the glass with a piece of translucent Plexiglas to accomplish the same result.
Assemble the scanner/printer casing and plug in the light. You are ready to use your new light box.