AFAIK plastic card is sheet styrene. All the build articles I've ever sen that use it looks the same to me.
I've dabbled in alternate suppliers that seem cheaper, but it's either pebbly(for sale signs) or just not really usable.
Don I was permanently banned from the Computer Science Lab in Univ.
I was working on a big model of a building that had major sun control structures. So I went in and wrote a bunch of code for a series of punch cards that would be all holes. Back then you wrote the code in Fortran or what ever else you programmed in, and sat at a card punch machine.
I destroyed the machine.