Four Corners - Interlocking puzzle by Stewart Coffin (STC #6)

thingiverse

## ## Four Corners ### Interlocking puzzle by Stewart Coffin (STC #6) Assemble the six pieces into an interesting polyhedral shape with color symmetry, as shown in the cover photo. _Four Corners_ is a classic Stewart Coffin design, whose structure forms the basis for several of his later puzzles. Assembling the shape is straightforward; the challenge is to find all the different ways of assembling it with color symmetry. There are four different ways to do so, one of which is shown in the photo - can you discover the other three? Coffin wrote of this puzzle: "The assembled shape is intermediate between the first and second stellation [of the rhombic dodecahedron], and it has the symmetry of a tetrahedron. It serves as the skeleton for many other more complicated puzzles .... "The _Four Corners Puzzle_ is a good example of an interlocking structure with an intriguing geometry and attractive shape but which is trivially simple as an assembly puzzle. To make it also challenging, the concept of color symmetry is introduced. "... [T]o extract one more bit of recreation from this puzzle, discover the 24 ways of assembling it such that the patterns of all four colors are identical but not symmetrical. You may skip the 3,808 ways that do not have either property." ### Printing Instructions Print one copy of `coffin.four-corners.bases.stl` and four copies of `coffin.four-corners.tips.stl`. Ideally, use five different filament colors, with a neutral color (such as white or grey) for the bases. The pieces are assembled from multiple colors using "snap joints": simply snap the male and female connectors into place. If they come out too loose, they can be reinforced with a few drops of superglue, but this usually isn't necessary. The joints are designed to be printed without supports. In order to obtain the desired color symmetries, you _must_ attach the joints in the configuration shown in the second photo. To make this easier, the male joints on the bases are labeled with letters "A" through "D". Call the four tip colors "Color A", "Color B", "Color C", and "Color D"; then ensure all of the "Color A" tips attach to base connectors labeled "A", and so on. You may optionally print a two-color version by printing twelve tips all in the same color, in which case you can ignore the labels; but the five-color version is preferred. Also optionally, you may print `coffin.four-corners.bases-larger.stl` and `coffin.four-corners.tips-larger.stl` for a grander version of the puzzle, which will use around 50% more material. ### The Printable Puzzle Project The [Printable Puzzle Project](https://www.puzzlehub.org/ppp) aims to make available high-quality open-source models of many puzzle designs. All of our models are posted with the generous permission of their designers and are licensed for __non-commercial use only__. Anyone may print copies for their own personal use, but selling or otherwise monetizing them is not permitted, and puzzle designers retain all rights as copyright holders of their work. Our puzzles are modeled using the open-source [puzzlecad](https://www.thingiverse.com/thing:3198014) library. The `.scad` file is included with this model in case you want to modify any of its design parameters; more information on how to do this can be found in the PPP [Puzzle Modeling tutorial](https://www.puzzlehub.org/tutorials/puzzle-modeling). ### About the Designer Stewart Coffin has been called "the most outstanding designer and maker of interlocking puzzles that the world has ever seen". He is credited with over four hundred designs, has pioneered numerous ingenious puzzle forms, and has written extensively about puzzle design and craftsmanship. More information on Coffin, along with many other printable models of his designs, can be found on the [Stewart Coffin Puzzles](https://www.puzzlehub.org/puzzles/stewart-coffin) overview page. Happy puzzling!