The Mobius edge. Not the two dimensional object, the one dimensional curve. btw - I am just a re-awakening old guy trying to relearn math from the ground up. :) just so you know your questioner. I think I have worked out the parametric for a mobius strip. I get the classic x,y,z, coordinates for a strip with two variables. R constant at 1.0 for me. x = (R + L*Cos(A/2)) * Cos(A) y = (R + L*Cos(A/2)) * Sin(A) z = L*Sin(A/2) A, ranging from 0 to 360 degrees, L ranging from -Lmax to +Lmax, I use an R of 1 and a L approaching +/- 0.50 My problem, is trying to restrict the L quantity till it is just a single curved line. Eventually I hit a division by zero error in the graphing programs. I can make it draw up to some point (?) , like L= 0.5 +- .00001 and then I end up with just a very narrow two dimensional strip, not a line. Is there a simple equation to define the line or am I chasing a wrong path? Thanks.