So I'd like to make a pipe along the curve between the two concentric circles on the inclined plane and the two beneath the model (of course, the circles represent the outer and inner diameter of the pipe). I can make the pipe with the Sweep command, and open the end where it passes through the bottom of the model after unioning the pipe with the model. The end on the inclined plane, however, remains closed and I can't figure out how to open it. I.e, there's supposed to be a hole in the outer surface of the inclined plane leading to the pipe, put the pipe end just remains merged with the surface.

I can imagine pulling the curve and circles out beyond the surface and then deleting the extension, giving me access to the interior of the plane, but it seems to me that shouldn't be necessary. What am I doing wrong?