OPENING Puzzles (OPN) are puzzles in which the principle object is to open it, close it, undo it, remove something from it, or otherwise get it to work. They usually comprise a single object or associated parts such as a box with its lid, a padlock and its hasp, or a nut & bolt. The mechanism of the puzzle is not usually apparent, nor do they involve general assembly or disassembly of parts that interlock in 3D.

Zig-Zag & Coffee Cup boxes by Akio Kamei 1980s. Locks 17th century English through 20th Century Indian.

Boxes for Tobacco, Matches, and Snuff - some booby-trapped to spike unsuspecting fingers.
Scissors, Knives and Canteen sets with unusual unlocking systems which have inadvertedly made them into puzzles.