This cardboard is cut out of posterboard used for presenting things, like a science fair project. The board came from a dollar store. Before I started using this I was cutting up Amazon boxes lol.

If you want durable, good looking armour, you want to get yourself a hot air gun, and Wonderflex, and/or Worbla, depending on your needs. A bit expensive, but this is essentially what all those awesome WoW armour cosplays you see at ComicCon use, like Kamui etc.

http://www.kamuicosplay.com/ The bulk of these are moulded from wonderflex, for example.

Well, the nice thing about Wonderflex is it's a thermo-set plastic. So basically you heat it, it gets mallable, then you shape it. Don't like how it's turned out? Re-heat, then re-shape. The only problem with Wonderflex (compared to say ... Warbla) is you can't really join it back together after you've cut it, because it contains a fabric mesh inside it to give it some structure. So make sure you get the cutting correct (or give yourself excess that you can cut off after).

However, the fabric mesh means it's much more difficult to deform by pulling it in a way you maybe did not mean to. Kamui has a whole bunch of tutorials on her site and youtube about using these materials to do armour pieces, and how she prototypes etc. Check em out, see what you think.