Burr - a 6-piece puzzle in 3D

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Put it in front of a friend, let him look at it for 10 seconds (picture on the left). Then snap it with your fingers and see it explode (picture on the right). Ask him to assemble it again.

Based on a relatively simple module in A7 (74 x 105 mm) 6 pieces put together provide a "stellated, rhombic dodecahedron", i.e. a polyhedron with 12 identical, rhombic sides each of which has a (rhombic) pyramid raised in angles extending the adjacent sides. The model is created by David Mitchell who has a read-worthy description of a lot of geometric module models on his home page origamiheaven.com. He has also written a number of excellent origami books, see some of them at the book pages or search amazon.co.uk for David Mitchell origami.

I learned the model from Simon who once in the the early 90'ies got a single module from Thoki Yenn, with no further instruction. As an exercise you don't get any folding instructions either, except the knowledge that 6 modules are needed, and then the crease pattern to the left at the bottom (click pictures for larger size).

Two burrs

The pictures show two versions: one in thin cardboard, and one in plastic. The plastic version is difficult to assemble because the smooth surface makes the pieces slip more around. 80g copy paper is very suited for your first attempt, the cardboard only makes it a bit more robust.

The assembly technique to the right exploits that the paper is flexible. But an identical version could be made in wood and still be assembled. Hold the pieces that meet in the three frontmost peaks in the topmost left picture, and similarly the other three backmost pieces. Then the two groups just fit to slide into each other.

Similar wooden puzzles are known back from the early 1800-years as "burrs" (Danish: "tømmerknuder", timber knots), see e.g. Stewart Coffin's explanation. These are massive, a feature several folders have mimicked, e.g. Robert Lang, Jason Ku og Gadi Vishne. The latter has a diagram. Common to these are that they are made from squares and, with the extra extension on the modules, from a more complex crease pattern.

Dave Mitchell tells that his version is from 1989 and diagrammed by David Petty and possibly also Francis Ow, and included in Tomoko Fuse: Wonderful World of Modulars, ISBN 4-405-07553-0. Thanks to Dave for permission to bring the model and crease pattern on this page.