I’m trying to figure out how to build an offset shape for this. Imagine for example they’re streets, and I want to add sidewalks on the “street side” of every straight edge… Black edges are original shape, red lines indicate the offset I’d like.
the fastest way i can think off if you have a ton of them to offset or extrude the surface to a high value (for convenience that the upper surface just gets out of the way) use option solid then mark all the edges from an orthogonal view from the side and use ChamferEdge followed by CurveBoolean, click inside and level the result to the initial hight, remove the solid.
Another way that could work is using ExtrudeSrfTapered on the surface with an angel of 45 degrees and solid=yes. Then enter the same distance you want to inset as a height. Then run DupFaceBorder on the newly created top surface.