I’ve tried playing with Sandbox and also reading other discussions but nothing is doing what I need so far. I’m going to be very specific.

I have 4 points. Two of them lie at ground level, and the other 2 lie a little above ground level, both at the same altitude. The two points on top lie almost right above the 2 at ground level, but not quite. One is a little on one side, the other is a little on the other. That means these 4 points don’t lie in a plane, and if I put lines around them, Sketchup cannot fill the almost-rectangle because it wouldn’t be a flat surface.

I want it to get filled with a smooth surface that twists slightly. Ideally I would like this to happen in such a way that horizontal cross-sections of the surface are all straight lines, going continuously from the straightly line between the bottom pair to the straight line between the top pair.

My way of doing this has been to fill in the region between my points with triangles, color them, then hide all the edges. This gives an approximation of the surface I want, but is a little off, and is tedious to make.

Might anyone suggest a faster and/or more precise way of making the twisted surface that I want?