+1 to TUBE renovation. Working around the twisting is very cumbersome, and it’s surprising that the angle argument doesn’t help it. When you renovate TUBE, take a look at how a cross section with sharp corners renders in OpenGL. It seems to assume that TUBEs are generally curvy. To get around this, I have resorted to a chain of mitered PRISM_s. The trouble with that is the contour of the curve becomes invisible. I’d like to see something like PRISMTUBE, where we have PRISM_ type status codes, but it can follow a path.