Hi, I want to make a surface whose outer boundary follows a mathematically defined 3D curve and inner boundary follows a planar circle. I tried using loft with the 3D curve and three circles (because I am trying to bend the surface down to one plane in the inside), but the surface appears as if it is being wrapped around the three inner circles. I also tried fair the outside 3D curve (as the tech of McNeel), the problem still exist. Is there a way to get around this problem?

loftQuestion.3dm (672.3 KB)