An artist by trade, Greg goes dumpster diving. Not because he's poor or living on the streets - but so that he can build small, one roomed shelters for the homeless.
The 'homeless homes' resemble tiny sheds, and are only about the size of a sofa. But despite their miniature nature - they mean the world to the people living in them, who are used to staying unprotected on the streets.
With pitched roofs so that the rain runs off them, and set on wheels so their owners can move them if needs be, the homes are usually made from the foundation of discarded wooden pallets.
Greg scavenges through illegal rubbish tips and official dumps to find what he needs to create the homes - which look pretty professional from these pictures.
A sculptor by trade, Greg could be making big bucks selling fancy art for someone's home, but instead - he's decided to give something back to the Californian community and help those most vulnerable.
This just made us go all warm and fuzzy inside.