My own thread about my DIY Acrylic Reflector for 580EXII =)
Only con? It's slightly heavy and, since I'm small, mounted on my Gripped 400D, it's the exact height of my shoulders to hips. People might look at you as if you're crazy if you bring it out in the open to shoot.
You can buy the zebra card at 100 for $30 if i'm not wrong.
I don't know where to get them as
my company uses it and they have some spares that i take.
So far it has been very durable and i've only used one for about a year.