Armstrong is represented by the John Pence Gallery in San Francisco.
From their site:
His work is most unusual for the big city in many ways - Armstrong is a Kentucky native known for his "Automata" sculpture. Every piece has moveable parts, hand-carved from various woods and vividly painted. He deftly uses gears, pulleys, chains and the viewer's energy to make his sculptures move. They stand tall, they whirl and spin, and they open to reveal an amazing sense of humor.
At this moment, he has a piece on auction at eBay.
Check out the John Pence Gallery's page dedicated to Steve Armstrong's automata.