Please have a look at the picture of a guitar I have modeled in Rhino. There is a feature called a belly-cut (or tummy-cut) that is relatively straight forward to do with a 2-rail sweep when I have access to put one of the rails on the side of the guitar body and one on the back. Since the rails are offset in the X, Y, AND Z axis, the resultant surface varies in pitch, or steepness, along its length. Additionally, I am able to control the max depth (1 inch in this case) and the location where that max depth occurs.
Is there a way to create such a feature in Aspire?