I only need that capability rarely, and when I do, I use the same templating technique that stone countertop installers use.
I keep some 1/4” thick scrap plywood on hand, which I keep ripped to a 2” width.
I lay pieces in place where I want to measure, and using a glue gun, I attach the pieces in place locking in the angles.
I also use this method for sizing large format tiles. I can accurately transfer complex shapes, including wall outlet openings without resorting to the use of rulers.
Of course, if you need this capability often, then some sort of dedicated jig might be useful. But the countertop people use this method a good deal, and they stick with it until they get a very expensive laser measuring system.
This guy uses cardboard and crazy glue. I might try that next. But the same concept. If you don’t need the rigidity, that might be easier.