Was reading a recent thread about how we all scrounge for tools, often in the strangest places. I have another "gold mine" to tap for getting a large supply of squeegee material.

The plastic slats from window treatment vertical blinds (especailly for sliding patio doors, large picture windows, etc.) can give you 7'+ long strips of readily trimmable squeegee material. Many slat designs have a slightly rounded "rib" as edge treatment. This is great for helping hold/guide a pool of epoxy during the "skimming" step. You can easily cut the slats to any shape with a scissors.

Suggest contacting local schools, hospitals, office buildings, etc. that have many windows and are often replacing/redecorating. If/when you find a remodeling going on, you'll walk away with enough squeegee material (and a myriad of other possible uses) to last for years.