green screen

I want to shoot some video and use it with animated elements and backgrounds, so I have to film in front of something called a green screen. I don't know where to find such a thing to rent, so I "Cheapy Chee'd" it and bought 24 yards of bright green fabric at the Textile Clearance House - I'll make my own green screen!
The poor woman who had to cut the fabric for me, she asked me to repeat how many yards I needed three times because she couldn't fathom the idea of anyone needing 24 yards of bright green fabric. As she measured out the fabric yard by yard, I tried to think of what she might imagine that I would need this fabric for.












...

Surely I won't need ALL 24 yards of fabric for green screening, would I?