Has anyone custom fit louvers before?

Looking to stick a rear windshield and quarter glass louver setup to my car

Given its a 4 cylinder soccer mom sedan, (hyundai elantra) the demand for muscle car esque fittings is very slim

I am a broke douchebag and just like the look of them, and im looking to make my own.

What is the best material for sun deflection back there? What things should I keep in mind during construction? Thanks