Like Brain Teasers? This DIY Puzzle “Nails” It

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Like Brain Teasers? This DIY Puzzle “Nails” It


I love brain teasers and wood-based puzzles and this is a good one that you can easily make yourself. Basically, all you need is a chunk of pine, a nail, and some boiling water (oh, and a saw and a drill).


It’s called the “Tooth and Nail” puzzle, and it appears to be an optical illusion. It is not.

SPOILER ALERT: How this works is fascinating. After three sections are cut from the wood, one of the remaining “teeth” on the end of the puzzle is saturated in boiling water. This allows the soft pine wood to be significantly compressed enough so that a hole can be drilled through the two center teeth to accept a nail. As the wood on the compressed tooth dries, it returns to its original shape and the illusion is complete.

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Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. His free weekly-ish maker tips newsletter can be found at

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