The Development of a Fixed Polarizing Filter

Bobthearch wrote:

The material looks similar to something we used at work for covering red LED screens mounted in control panels.

Actually, it looks like standard smoked/bronze acrylic sheet material. I actually have a piece in my basement left over from a project two decades ago. It is commonly used as cover for LED displays to give an even, featureless, background; that's how I used it for a network status display on a little sub-$10,000 cluster supercomputer I built for a competition at IEEE/ACM SC2000 -- see the dark squares on top of the cluster:

The KRAA Z-MP Cluster Supercomputer; Acrylic panel over LED network status display

That material is NOT a polarizer, but a slightly brownish dark tint transparent plastic. So the "fixed polarizer" the OP has "invented" is probably nothing more than an acrylic tinted ND filter. BTW, it's pretty common practice to hide a camera behind a sheet of this material, so shooting through it is a well-known thing.

This acrylic normally comes with a protective plastic film over it, and can be cut cleanly with ordinary saws that have relatively fine teeth (typically used for metal cutting), especially if you stiffen it by sandwiching it between sacrificial pieces of a material like hardboard or wood. The score & snap method can work too, and it also cuts cleanly with a laser cutter (although you'd want more power than my little 2.5W laser cutter and great filtering/ventilation: laser cutting acrylic materials with unspecified additives can result in quite toxic gasses).