Here 'an interesting project I did in just two days. I spent time chatting to Downtown LA's homeless a few weeks back. They make a small living redeeming aluminum cans for 2.5 cents each.
I figured you could add value to this free resource and on sell it. Homeless with half a bit of motivation and skills could do this, make molds and create something out of the metal to sell. This is just the furnace but the harder part. https://www.youtube.com/watch?v=TAmfExh7D00