The sunglass visor clips I've printed have all lost their grip and tend to slide off the visor when you operate it. Or they pull off when you try and remove the glasses.
Here I've made a clip that clips around the back and front of the visor so that it won't move or slide off.

It also has two notches, one for the ear pieces and one for the nose bridge. Might need to adjust the width to match your specific glasses.