You will need tin snips, heavy duty gloves, nail and a hammer.
Carefully remove the top and bottom of the can, then cut a line down the side so you can flatten out the can.
Cut out your star shape and use the nail and hammer to punch a design in it.
Just the edges I am a bit unsure about so they arn't sharp.
Might find more information on this site
http://craftzine.com/projects/