Where to get cage building material?

I've been trying to find out what basic bird cage material
is called, because I want to buy some plain panels and
make my own cage out of material like this:

http://images.netshops.com/mgen/digimarc.ms?img=master:PRP052.jpg&h=400&w=400

Does anyone know what that stuff is called, and/or where
a person can buy some?

Thanks,
David