[Chris]

I also use OG to make physics-related diagrams, and I find magnets very frustrating. They never seem quite designed to work the way I want them to. I've gotten to the point where I just ignore magnets completely, and turn off "Allow connections" in the inspectors. So I can't really help with that.

But I can tell you how to make new shapes. I've made a lot of new shapes---parabolas, sine/cosine parts, various circuit parts (resistors, inductors, etc.) There's a tutorial here. It would be pretty simple to make a shape that was just a line. Actually, now that I look at OG, I think there's already a shape that's a line; it's in the inspector right after the jigsaw piece and the delete shape. I don't think that's one that I made myself ...

If you want an example of making a new shape, I posted one in this thread a couple days ago.