in my opinion, no.
cardboard is too soft and isn't going to take a compound curve, and plasti-dip isn't rigid, so it's still going to be bendy, flat armor.
after filtering through the color codes in your post, i see that you are basically asking a lot of questions about a lot of different materials. please consider using the search feature on the board. most if not all of the questions you've asked have been answered many times over.
in the end, it all depends on what you want the end result to be. if you're looking for a halloween costume you can build it out of just about anything. if you want a screen accurate boba fett costume you really don't want to try to cut corners using cardboard and plaster of paris.
