Using pop cans is not likely to be very successful. First you will need an awful lot because they are very thin and light, second when you melt them a large percentage is burned away as oxide.
One place you could try for aluminum scrap is car wreckers for rims. You should try finding some books about casting aluminum. It is fairly easy to make the patterns and actually cast but then working with what you have cast by drilling holes and tapping threads may be very difficult. Most aluminum alloys whether cast or extruded or heat treated for greater strength and better machinability. Not to say you cannot build something but you might encounter less frustration by getting some background information first.
An open mind is a virtue...so long as all the common sense has not leaked out.