Here at TardHaus, we like to recycle our aluminum cans. In typical TardHaus style, we don't do it the same way most people do. Instead, we melt the aluminum (using a charcoal-powered blast furnace) and use green-sand molds to make whatever we want. The extra melted aluminum goes into a muffin pan to make "ingots" that can be remelted later and made into more stuff.
I took a couple of these ingots and decided to try them out on my CNC mill. It's an EMCO F1-CNC milling machine that was retrofitted by students from Vermont Technical College with new stepper motors, gecko drivers, and Mach 3 software.
After milling some flats on the sides so my vise could grip the ingot, I milled the face and then played with cutting a circular pocket.
Then I played with machining heatsink fins.