These things rule! It's worth your time, trust me!I am such a little cheat--I got this from the webbysite http://home.xnet.com/~aak/hexahexa.html if anyone would like to see the actual page or find out why it's called a hexahexaflexagon or anything like that. Try it, you'll probably like it. So, let's get started.
First cut out a looooong strip of paper. Fold it into nineteen triangular sections with 60 degree angles at the corners. It's really not that hard if you have a protractor or something like that. After you get the first fold, the rest you can do by folding the paper back over itself, but remember: there MUST be sharp corners on this. ABSOLUTE MUST-HAVE. Then number as shown below.
Fold the strip of paper so that the 4's touch the 4's next to them, the 5's tough the 5's, and the 6's touch the 6's. It should look like the below figure. Fold on the "FOLD FOLD" line.
The figure should look like the one below now. Fold back on the "FOLD FOLD" line.
The figure should NOW look like the one below. (Gee, deja-vu.) All that's left is to fold the last "1" flap down and glue (tape, staple, etc) to the flap behind it.
TADAM! Done! You have a hexahexaflexagon! Now all you have to do is learn to use it! Now, fold in every other fold so it looks like a three-sided pinwheel. Now you can fold it down from the other side and get different numbers (the first side was all 1's and the other was all 2's; now it's 2's and 3's). You can cycle through all the numbers eventually, if you get the hang of it. Have fun!