I got into a minor craze revived by Vi Hart over the construction of hexaflexagons some months ago when her video first came out. Around that time, I made a video which I only got around to posting on YouTube only recently. There are a lot of things regarding hexaflexagons that have representations in combinatorial graphs containing some combination of un-directed and directed edges. They are fun to make, and unlike what appears on nearly hundreds of video blogs on the topic, I decided to use as few techie gadgets as possible (except for the paper trimmer used to make the strip in the first place). No ruler, no compass or protractor, and I was so busy concentrating on folding (while folding is not complicated, it is also not exactly straightforward either) that I stopped counting triangles, and had to count after the fact. It was exactly 19 triangles anyway. The folds were also as close to 60 degrees as I could have hoped for.
I’ve provided a link so you can watch the video here: Hexaflexagon_Construction_-_the_slow_way