Friends, thanks for the interest in my project! This is so fun to make, I hope you'll try it and give one to a friend! Flexagons are just for fun and apparently really popular with the math world. Please click on the link I've posted to watch a video clip of it in action!
I posted my instructions and procedure steps on page 2 of the comments. More questions? Just ask!
No there is not a pattern for the diamond, you have to draw one up yourself or possibly find one online. It's easy to do though! Draw an equilateral triangle (all sides the same length). I made my sides 3". The angle is 60 degrees on an equilateral triangle. You can use a protractor to measure or I found degree lines on my cutting ruler! Then trace the triangle (so you have two), cut them both out and put them together, making a diamond. Don't forget to add a 1/4" seam allowance at this point! Keep one of the triangles for the broken diamond pieces on two of the rows. Don't forget to add the seam allowance to all three sides of that triangle.
Yikes I hope that helps! I don't know how to update the original post to put all this info together... I will if someone can tell me how.