Making a 6 FT Ninja Star as my first prop, tips and or tricks to help?

So I've seen some of the so called "Giant" ninja stars/shurikens out on the web, but the biggest one I've seen is maybe about as big as my arm. Since that just doesn't do it for me, I've decided that my first prop is going to be a shuriken about as long across as I am tall. My main worries here are Stability (As little flex as possible), Weight (As light as I can get it), and Durability (Don't want it to break easily).

Any tips on materials, framework, and that sort of thing?