Viewing negatives without a light box can be difficult and cause eye strain. By making a good-sized light box, you can compare multiple negatives strips and get a good sense of negative densities. Your light box can be easily made from readily available components. In addition to viewing negatives, your light box will also work well for viewing slides or any other film-based image.
Paint the inside of the box white. This will help reflect light upward.
Drill a hole in the side or back of the box. This is for the power cord for the light box's light fixture.
Thread an electrical power cord through the hole in the box and attach it to a 20 watt strip fixture. Many 20 watt fixtures are around 2 feet long and will fit easily in a 3-foot-wide wood box.
Screw the fixture to the centre of the wood box.
Put a small screw on the inside of the box corners about halfway up the box. This will support a light diffuser to help create a more even light.
Slip a piece of frosted or translucent Plexiglas down onto the screw supports to act as a diffuser. Measure the interior dimensions of the box and cut the Plexiglas to fit.
Place four more screws near the top of the box for the top viewing surface and slip a second piece of translucent or frosted Plexiglas on top.
Take the viewing surface and the diffuser out and install the fluorescent tube and igniter. Plug in the box to make sure the light works and reassemble the light box.
If the diffuser cuts too much light and you aren't able to dim the lights in the room, remove the diffuser layer. You will, however, have more of a hot spot toward the centre of the light box. If you are planning on using your light box for long periods of time, consider adding a small computer fan on the side of the box to draw out heat.
Don't use frosted glass with screw supports. The corners of the glass have a tendency to break. If you want to use glass, make supports out of very thin moulding before painting the inside of the box.