Make your own photographic emulsion
By James Grahame
If you're tired of paying The Man at Kodak or Fuji, why not try your hand at creating your own photographic emulsion? This silver-based mixture is intended to be coated on glass or film (yes, you get to play with a squeege). You'll need some sort of large-format camera that can accept a photographic plate (this technique will work wonderfully with a simple homemade pinhole camera as well).
The ingredient list reads like a toxic flavor of Jello: Gelatin, potassium bromide, potassium iodide, and silver nitrate. Remember that your emulsion is light-sensitive and you'll have to work in a darkroom with illumination from a safelight. If you're not adventurous enough to mix your own, you can buy premixed liquid emulsion from Photographers' Formulary.
Make a simple film emulsion (via a thread started by Paul Cotto at filmshooting.com)