Usually, I just use my handy roll of newsprint (oh, how I love my roll of newsprint) and paint it with my children's Crayola craft paint, but I thought it would be awesome to do this one like the Sesame Street Sign to match the invitations. That would have taken a lot of green paint to fill in, so instead I bought three sheets of green poster paper. I trimmed two of them to be a little bit narrower, and on the other I drew a large half-circle free hand and cut it out.
I taped them all into position so they wouldn't shift when I started with the paint.
Since I wasn't working with white newsprint, I wasn't sure if the regular kiddie paint would show up well once it was dry. Happily, I had some leftover paint from making my children's puppet theatre a couple of years ago, and it was still good. I used a sponge brush and painted on the yellow boarder.