Clip this to your car visor and it will hold your sunglasses.

After the one I use broke, I decided to make my own improved version.

One thing to note is that this item requires secondary materials and assembly, including some 14-gage spring-steel wire (1095 or the equivalent) for the visor-holder wire, a short length of 12-gage wire for the hinge, and some neoprene rubber glued in to hold the sunglasses in the center.

All parts have been modeled separately to facilitate building and dimensional guidance.

I assume one day that 3D printers will be able to print foamed-rubber, and various metals, and then something like this would a one-shot production, but for now it's an assembly.

My major innovative change is to improve the durability and strength of the clasp, which is the major failure point of the device, through use of a flexure-based design and copious use of filets which avoids sharp 90° corners that act as stress-concentrators, and tend to be where breaks propagate.

Here's an example of this kind of clip that you might find in any corner gas-station:

http://i.imgur.com/n5hzvmp.png