Cool new hobby?

Steganography. The digital uses of it are over my head, but I can dig the mechanical, chemical methods. For example, an extremely crude technique for concealing files is to cover your paper with wax paper as you type (on a typewriter). Then remove and destroy the wax paper and sprinkle some cinnamon or some other fine dark powder on the paper. The powder sticks to the dim but readable wax-impressed letters. Voila.