Puzzle Box with Changeable Combination. With some waterproofing, or hidden in a tight container, this could make a good field puzzle
Instructables: Picture of The Enigma Puzzle Box Enigma project?
Vintage Box 1889 Singer Oak Puzzle Box and Sewing Machine Attachments
Being a little addicted to my Trotec lasercutter, I had to design a puzzle box.This box has three dials, connected with each others with gears. The middle gear is...
This was my very first project on the laser cutters at the TechShop, and I am indebted to Bruce Viney for supplying the plans for the project.
How to: Make a Simple Wooden Puzzle Storage Box Mehr
Puzzle Box (Unabox): 14 Steps (with Pictures)
Diamond Locking wooden book [Need to see if I can duplicate this trick; there's a box out there somewhere and the center square changes color when unlocked]