@Zablorg Is this what you meant? Please give a clear explanation of what you're asking and straight to the point. Also please show us some of your 3D work because we don't know where you're struggling with. Thanks.
Zablorg: You can use as many segments around the cylinder as you want, and place them anywhere, without affecting the form. So in your last post, there's no reason to move both control points away from the corner like that.
Also it's important to establish to which degree you want the object to be parametric. Which would the parameters be exactly?
How would you guys make a diamond-patterned bag with the least manual tweaking? I tried creating a bag from a quadsphere and twist it at the top, then convert that to splines, then mirror it for the opposite cross line. The problem with this is the bag loses its pattern shapes at the bottom, plus it requires quite a lot of vert pulling. I also just created a subdivided plane and pulled the center down using soft selection, but it deforms awfully.
i wont use ngons