Build accessoires for your digital camera by yourself
Ring light with 16 or 24 superbright white LEDs (New version)
Ring light with 8 superbright white LEDs (Old version)
Use a 500mm SLR tele-lens as a telescope
Cheap filter for infrared photography
Tripod head for panoramic photos
Handle for external flash unit
Other DIY projects:
How to produce printed circuit boards (PCB)
Cuvette for etching PCBs - made out of acrylic glass