1. Draw your skull on the rough side of Shrink plastic using pens. This keyring used a 1/4 A4 sheet (the earrings an 1/8th). Beware the colour get darker once it shrinks.
2. Once your happy trim the skull (doesn’t have to be exact 3mm or less edging is fine). Punch a hole in the top for the keyring to go once it’s shrunk.
3. Place the skull in an electric oven (150ºC) on a flat baking tray, drawing side down and heat for 1-4 minutes until it goes flat. Allow to cool and add your keyring, earring or phone charm.