/diy/ - Do It Yourself

Help me out, /diy/.
I want to make a shield for a LARP event because I'm not feeling like throwing 150 bucks for a piece of foam.
I had the idea to make a shield similar to pic related, covering the arm and the forearm. The thing is, I need to shape it in order to make it look acceptable.
So here's my problem: I need to use some kind of material that can be easily cut and bended (And possibly curved) to make the support of the shield.
It must be resistant enough to be able to take light hits without breaking or deforming.

I don't have a lot of tools (Well, I do have your regular common tools, but I don't have anything electric or for a specific usage.)
So according to you, what material could I use?