Originally Posted By: hybrid8
The way I imagine working the puzzle is to move (rotate) the lid about its hinge with the spring ends fixed to points I've set.

Okay, then set the endpoints and move the angle slider.

You don't really need to look at all the intermediate points in the opening and closing, though; it's not going to do anything but compress as you close the lid. Said another way, the fully open position will always be when the spring is at full extension, and the closed position will have the spring as compressed as it's ever going to be, once installed.
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Bitt Faulk