Get a plastic "For Sale" sign. Trace your design onto the sign 2 times. Make the pattern a little bit smaller if you can. use an exacto knife to score the sign. you should be able to just pop it out after scoring. Double up the two pieces. Hot glue will work pretty good because it's basically a plastic and will be somewhat stiff when dry. Layer foamies over the plastic pieces. Check for any sharp points sticking out and trim them for safety.
Won't be rock hard, but will be ridgid and flexable. Which will be a good thing if you are in public anywhere.
That's how I did my blades gaunlet.
