The material can be either stretchy or not and varying degrees of smoothness from very grainy or "embossed" to glass slick. Some panties are smooth on one side and grainy on the other Some materials, while smooth on both sides, are smoother on one side than the other. Grainy material tends to tear more easily.
The material can be anything from moderately thick like the Comco to almost tissue-paper thin. Generally for materials that are going to be near the body or get a lot of use other than for decoration, you wnat medium or thick material
The material can vary in appearance from crystal clear, to transparent to semi-clear or frosty to translucnet to opaque and, within these tkypes can have color or not. thus there is semi-transparent pink. There is also print material that is a material, usually opaque but not always that has designs on them.
Becuase of the feelings that rubber has created about being reduced to a baby, there has been some attempts to move away from it for waterproof panties to spare the feelings, particularly of boys who are implicitly aware of the very feminine nature of rubber as well. We view this as foolish and to us, if you wet then you are a baby and a baby girl at that and we fully support the idea that this is what you should be dressed as; whether you like it or not.