masking tape/painter's tape
metal food tins
Check your local thrift stores for metal tins - they seem to be everywhere! I went to the Depot for Creative Reuse
in Oakland, and they had a huge selection of them - I got four of them for $2.50.
Or wait until the holidays and dig in your neighbor's trashcans.
As far as paint, make sure you're using something made for painting metal. I'm using Rust-oleum because I've had success with it before. And the ultra cover stuff I'm using works really well. :D