You will need: Tin foil.You don't have to buy it, do you have Milo, milk powder at home? newly opened or not yet open, you will find it inside the tin.Instructions: all you need to do it's put the foil on the ruler (where the hole is) , then slightly press down and pulling it to the edge to get the shape, then use needle to jab some little holes in the middle, cut it out and it is done.