I heard back from one of the companies I reached out to regarding the original material that was used to make the outer skin of the cape. The guy I am speaking to says he recognizes the pattern, and says it is an industry standard. He is going to send me a sample, and I have also requested pricing on some material in case I want to revisit the cape from the ground up.
Though this may seem like an expensive and unnecessary alternative to the mold I have off a hero cape, there are a few factors motivating it. The mold I have has some flaws, and also some limitations. It is also really hard to transport. If I can find the source material, I will be able to recreate the mold any time I want, and can also create it out of different materials. For example, I could do a rigid mold, which would give me some additional freedom in what material I decided to cast in.