The heptaflexagon has 7 triangles meeting in the center.
You might expect the heptaflexagon, with 7 triangles per face, to not flex very well, but it has some intriguing possibilities. Unlike the pentaflexagon, you can actually get it to lie flat with leaves from faces other than the two primary ones. If you try to use the same pinch flex as you do with a hexaflexagon, you’ll be able to flex it into a configuration with 6 triangles per side with an extra little tent sticking out of one side. From here you can do other pinch flexes in various places, some of which will mix up the faces.
Cut out the net and pre-crease all the edges. Copy the small letters and numbers on to the back. With this first net, fold 1 on 1, 2 on 2, etc. When you get to the 7’s, fold one flap under the other so the 7’s face each other. You should now have a heptagon with A’s on one side and B’s on the other.
With the next net, start by taping together the two strips so that g/3 is next to 4/h. Fold adjacent lower case letters on top of each other, a on a, b on b, etc. Next fold adjacent numbers on top of each other, 1 on 1, etc. The final step is to tuck the final flap under so the 7’s are on top of each other. You should now have all the A’s on one side and the B’s on the other. Tape the flaps onto the A and B faces. I recommend taping them in such a way that it’s easy to take it apart and refold if you get lost.
The first hexaflexagon style pinch flex should give you a face with three pairs of numbers on it. Which three depends on where you flex. You can then flip it over and do another pinch flex to get a face with three pairs of lower case letters. From here, there’s a tricky move that will then give you back a flat heptagon with the faces all mixed up.
Next: The Octaflexagon
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