If Rob McElwain isn't standing on a downtown street corner protesting the ongoing abuses of Maricopa County Sheriff Joe Arpaio, he's probably creating his colorful, hand-painted signs with biting anti-Sheriff Joe messages. Eschewing traditional art supplies, McElwain scavenges cardboard box "canvases" and buys discounted buckets of rejected custom-mixed paint from home-improvement stores to create these brutally critical works.