An angle changer is a piece of material that can change the angle between two parts of an object. You can change the way sunglasses fit by changing the material or thickness of an angle changer. An angle changer can be glues, magnetically, etc . . .
FIGS. 1, 2, and 3 show the place where you would put the angle changer. FIG. 5 shows a poor fit in a pair of sunglasses. In FIG. 4, you can see that by placing an angle changer, it makes the sunglasses have a better fit. In FIG. 6, y is the opening of a poor fit of sunglasses. By placing an angle changer you can see opening x, which makes the sunglasses have a much better fit. The angle changer is not limited only for sunglasses.
I swear on the best of my knowledge that I'm the inventor of the angle changer.