Subject: what would it take to melt an aluminum can w/ only sunlight

in the same manner as it is possible to take a plastic action figure and a 
magnifying glass and eventually reduce it to a molten state, what would it 
take to do the same to an aluminum can?? What hardware would be required to 
experement with this, my goal is to turn an aluminum can into a molten 
state (for casting) using only sunlight if it is possible.  thanks 

Re: what would it take to melt an aluminum can w/ only sunlight