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Face-Turning Octahedron
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The first face-turning octahedron with straight cuts.

This puzzle is commonly referred to as the "FTO" for short.

Karl Rohrbach filed a patent which was granted as DE3206560 in 1983 but nothing happened afterwards.
The first workable mechanism was designed and prototyped between 2001 and 2003 by David Pitcher. A US patent application was filed in 2003 and allowed in 2005. However, issuance fees were not paid, so the patent was never formalized, and the invention became public domain.
Although this puzzle was not commercially produced before 2008 it became very fast a standard puzzle every collection should include. This happened because it is the first octahedron (one of the five platonic solids, the most regular solids geometry knows) with one planar cut parallel to every side.
Before this puzzle there have been:
- the Rainbow Octahedron without planar cuts.
- the Magic Octahedron which looks like this but twists around its corners and is therefore a 3x3x3-derivate.
- the Dino Octa with shallower cuts which never made it into mass production.
- the Skewb Diamond, which is deep-cut and has fewer pieces.
There has also been the Master FTO, which can be viewed as a) a deep-cut plus shallower-cut puzzle like a 4x4x4 cube or b) a combination of Skewb Diamond and FTO.
Edge length: 75 mm
Weight: 159 grams

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Contributors

Thank you to the following people for their assistance in helping collect the information on this page: Andreas Nortmann, David Pitcher, GoombaGeek.

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