re: â€¦As the bend tool only seems to work from a straight edgeâ€¦
You can use a Line object as an edge from which to create your bend. The line has to be on the face where the bend is to occur.
In the case of a sheet of paper, you may want to take a Rectangle, then use "Format / Create Surface / From Profile" on it, then use the Bend tool on that. It's basically a Facet, but the program thinks it's a solid.
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Windows 10 Pro (1803), 64-bit