Woodcarving Magic by Bjarne Jespersen is subtitled “How to Transform a Single Block of Wood Into Impossible Shapes” and includes instructions pocket-sized “gizmos” such as puzzles, cages, spheres, chain-links and more — with geometric explanations of how they work. Woodcarving Magic (Fox Chapel Publishing; ISBN 978-1-56523-523-6) is priced at $19.95.