A mechanical puzzle is a puzzle, involving several objects or a single object composed of one or more movable parts, whose solution requires moving from an initial state to a predefined final state. Mechanical puzzles were first classified by Louis Hoffmann in Puzzles Old And New (1893).¹ A modified form of his scheme is shown in the table below. Click on the links for further details.

 

type	subtype	example(s)
assembly	2-dimensional assembly 3-dimensional assembly matchstick puzzles miscellaneous	Tangrams, T-puzzle, jigsaw Soma cube puzzle rings
disassembly	trick or secret opening miscellaneous	puzzle boxes trick locks, keys, etc
interlocking solid	burr puzzles 3-dimensional jigsaws interlocking	cubes, other objects
entanglement and disentanglement	wire puzzles string puzzles miscellaneous	Chinese rings cat's cradle
sequential movement	counter removal counter rearrangement sliding-piece miscellaneous	peg solitaire Fifteen puzzle Tower of Hanoi
puzzle vessels	puzzle jugs miscellaneous	bottom-fill teapots, pitchers
vanishment puzzles		Get Off the Earth
folding	origami flexagons
impossible objects

 

References

1. Hoffmann, Professor (Angelo Louis). Puzzles Old and New. London: Frederick Warne, 1893. Republished privately by L. Edward Hordern, 1993.
2. Slocum, Jerry. Compendium of Mechanical Puzzles. 3rd ed. Slocum and Haubrich, 1977.