Hand-held light meters have been standard tools of professional photographers since they were invented. They can give more accurate lighting information than in-camera meters and help you get better exposures. While you can acquire both new and used hand-held light meters, you also can build them yourself.
Basics
In order to make your homemade light meter weigh as little as possible, don't use wood or metal for your project. The best housing for such a meter is a small plastic box sturdy enough to work with but light enough to carry easily. One such plastic box is a travel case for a bar of soap. You also need a light sensor and the internal workings of a light meter. If you want to avoid using batteries, then you need a photovoltaic sensor, such as one made of selenium.
Cutting
Cut a hole in the plastic box for the light meter's needle display. You can glue in the needle display from underneath if you cut the hole big enough for only the display's face. Connect the display to the meter workings via wires. Then cut a hole in the short end of your plastic box for the photovoltaic sensor. The sensor may be glued in place. If you want to protect it from overuse, use the piece of plastic you removed from the plastic box as a cap for the sensor.
Other Tasks
Attach an eyelet to the end of the plastic box that is opposite the sensor, and then to the eyelet connect a neck cord, which allows you to hang the meter around your neck while photographing. If you use a plastic soap box for this project, you can glue it shut; if the plastic box has a snug fit, however, just leave it as is, enabling access to the meter's inner workings to repair a problem or replace parts.
Instead of a plastic box, you can use a small metal box such as a cough drop or mint box, which provides sturdier casing. Make certain, however, the box is big enough to hold the meter's workings before you make all the cuts. This type of box will give you access to the inside of the meter.
Tags: light meter, light meters, meter workings, needle display, photovoltaic sensor