I made this sign out of a mattress box. It measured about seven-by fifteen feet and was visible to all lanes of traffic on the 580 by the Richmond/San Rafael bridge. The sign took less than an hour to make and cost about fifty cents in materials. Using a hammer and nails it took less than a minute to post and stayed up for two days.
(This image should be considered as part of the public domain. Feel free to use it on T-Shirts, bumperstickers, or any other commercial or private endeavour. Go Wild. )