Get a can making sure it is clean and dry
Cut the top and bottom off
Cut straight down so you can lay it out flat
Cut so that there is a nice edge
Fold one side into the middle
Next cut a piece of wire about 1/2 shorter that each side and carefully stick the wire in the middle with a bit of tape
Fold the edges up.
Then fold the last bit over
Now spend a little while bending it to the shape of your wrist.
Now run along to make you can cuff