I've come out with a new material. It's a smooth black plastic, identical to the original 1960's glasses. They cost a little more, but no processing for you! They are flexible and I have tested them for breakability. They are more rugged than previous model. When ordering, select the "BLACK PREMIUM".
You can still buy cheaper version: with the rough surface for less money. This model is called "BLACK NATURAL". They can be painted smooth if you want. For the white or black, paint with Rust-Oleum Flexible Rubber Coating. Really covers great! Gives it an original finish! Can be purchased at Home Depot.