I made my first set of wristblades from Plexiglas, and then I made a mold of them so I could make casts from urethane plastic. It looks like I'm going to have to make some casts again for my own wristblade gauntlet, since my blades broke in transit to Dragon*Con last month. (I knew I should have packed that stuff more securely...)
I might actually cast the replacement blades in a clear resin this time, so I can experiment with putting blue LEDs in there to light up the blades. Vinmanmac posted this idea some time back.