Quote - yeah, i'm kind of playing with it now and i think i see how to do it.  i still need to think about the math if i want it clean, but i think i see now.  thanks!

Now I think about it a bit more I think it is a question of movin the bottom verts of the tris.    If you pull one out and bring it just over the center of the tri, then pull the other one underneath it, so that the tri kinda flips over, forming the underside of the pleat.

John

Fugazi (without the aid of a safety net)

https://www.facebook.com/Fugazi3D