Found a design for one by googling for a image of one.
The guy who designed it was in Europe. You could download the design from his web page for free. I found many people locally with 3-D printers and had someone print me 2 sets for $10. Canadian, about $7. USD.
It comes in 2 parts, the section that actually holds the lens, and the base that the lens holder can be bolted into, this allows you to swivel the lens up and down. I glued the base to a metal bracket designed to hold Bluetooth devices to a sun visor, the combination works awesome.
You might need to shave the lens holder with a nail file or a Dremel tool to get an ideal fit, minor adjustments at worst.
Took me 1 minute with my Dremel to get a perfect fit.
~Jeff