Rob & Mike,

Your best results will come from an F15T8BL florescent tube. They use standard florescent light fixtures. If you make your own light box, make certain that you reflect the light so it is uniform across the exposed surface. Without adequate reflectors, and if the bulbs are too close to the exposed surface, the exposre can become very non-uniform. It can vary sinusoidally with maximum exposure directly beneath the bulbs, and local regions of minimal exposure parallel to and between the bulbs. If this happens, move the bulbs farther away from the exposure surface.

On the other hand, if you can't, or don't want to, invest in any exposure unit, 20 minutes in direct noonday sunlight will do the trick nicely.

Good Luck,

Joe