Thanks for your suggestion to use an extension.
I’m a noob --and, because I don’t use SU often enough to retain more than a few of the fundamentals-- I’m reluctant to add more complexity by adding an extension.
OK, I’m willing to try. I spent a little time in Extension Warehouse, but I can’t identify what specific extensions to try from your description. Could you be a little more specific, please?
On this particular issue, it seems to me I’ve already moved from my original problem of drawing a rhombus to the apparently very different one of how SU draws/intersects circles.
Whew! All I set to do is to design a part to decently fit an out-of-square aperture made of wood. The first approximation would be a rectangle. Next better would seem to be a rhombus, but it seems that’s not so simple to accomplish.