Looking at the symmetrical elegance of Doug Engel’s EZ Unlink it’s not hard to see that he has an interest in the intersection between puzzles and sculpture. American artist George Odom’s 4-Triangle Sculpture was the inspiration for Doug’s puzzle. That sculpture consisted of four interlocking triangles with the midpoints of the three edges of each triangle fitting into the inner corners of the other three.
Similarly, EZ Unlink is comprised of four interlocking triangles; three of them have two slots each into which the other triangles fit. The fourth triangle functions as the key piece that locks and unlocks the puzzle. Doug explained, “There is also a set of three triangles invented by English sculptor John Robinson none of which are linked but held together similar to the Borromean rings. There were some puzzles using the Odom design at IPP gatherings. The ones I saw used magnets at the ends of dowels or wooden slats. These assemble into the linkage of George Odom and are not necessarily easy to do even if you have a drawing to go by.”
In contrast, Doug designed EZ Unlink so that, like the name suggests, it would be an easy puzzle to take apart and reassemble. “The idea was to make the pieces as triangles with slots. This means it is not a link system but is an ‘unlink’ since there are no links when assembled.”
EZ Unlink is part of a series of symmetrical puzzles that includes EZ Atom, EZ Galaxy and the recently released EZ 1. Doug said, “The idea was to make puzzles that are not so hard, are nice to look at and display, and represent a fun challenge that anyone can succeed at. Puzzles are a branch of fine art. [Miguel] Berrocal’s sculpture puzzles are fine art and very valuable.
“A good idea is rare so the next best thing is to design something that at least looks good and will probably enjoy a small but profitable year-to-year sales. Royalties are small but they certainly do help. You have to design as much for the manufacturer as for the audience. If it is too difficult to make, it will cost too much to sell.
“The audience for metal puzzles will be larger if the puzzle looks good and is a good challenge that has logical moves. It is well to recognize that this type of puzzle has analog features as well. You often have to position things at certain relative angles and positions for a solution. Some purists might argue this point but I feel it is valid. Metal prices are rising so lighter puzzles cost less to make. Fewer pieces are better and usually more elegant. I wanted to make sculpture-like puzzles that anyone could afford. Many of Hanayama’s beautiful metal puzzles fit this definition.”
Beyond the practical concerns of making puzzles that can be mass-produced and commercially sold, Doug focuses on the sculptural elements, likening mechanical puzzles to “beautiful jewels that must stand or fall on their own merits.”
He added, “Perhaps it is really the art aspect that drives most designers but perhaps not so much the inventors. Yet if you talk to puzzle people, especially those who also are into math they have very little interest in just the artistic aspect. They want above all else a puzzle that looks awfully simple but is very difficult. Also they want elegance: reduce to the fewest possible pieces that accomplish the task. These days if the puzzle does not look like anything, an animal etc., but is just purely geometrical and perhaps with a nice symmetry then that is what sells. With this assessment you would think Berrocal is out of fashion but his stuff still brings good money.
“I think almost everyone would agree on which puzzles are artistic and which are not so much. If you were walking along and found a puzzle on the ground it should immediately be obvious what it is. Someone thought it up and created it. Now others are challenged by it in pretty much a similar way as its creator. I have created lots of puzzles that I never solved, especially many of the circle puzzles. I could solve them and have solved some of them but in most cases was content to be able to create them as challenges for others who love solving more than designing and inventing. Jaap has solved many of them for me and posted very wonderful and thorough solutions with algorithms and usually some of the combinatorial math involved.”
Doug grew up in Western Kansas where his dad was a farmer, often spending time in his dad’s shop inventing stuff. “I guess I naturally grew up wanting to invent things. I was always sneaking to the garage and making something and got into trouble many times.” After university he got a job in Colorado as an automation engineer involved in industrial applications.
Doug was first introduced to mechanical puzzles by his father who brought home some bent wire puzzles. In college he invented his first puzzle, the Hexaflexatetrahedron (HFTH), an idea he came to after reading Martin Gardner’s article about Hexaflexagons, which first appeared in Scientific American in 1956 (and which incidentally was the first appearance of Gardner’s now legendary Mathematical Games column).
“I sent it to Gardner and he liked it saying it emulated Hexaflexagons. It was published a few times in various magazines and a book. The HFTH was first published in Recreational Mathematics Magazine, October, 1962, and later in various places. It is an assembly of six tetrahedrons held by three bands, one opposed to the other two to form a sort of double hinged ring. You can flex it into various shapes and so forth. Later Rubik came out with squares and hexagons connected in a similar way with fishing string so the string is almost invisible. I never was successful trying to sell it but did have a lot of fun with it. It is currently available as a cut out printed card model.”
EZ Unlink is available for purchase from Canadian distributor Puzzle Master Inc.
A selection of Doug’s puzzles and writing can be found at his website PUZZLeaTOMIc.