I love Julius!
Download a picture of Julius (or Clancy or whoever you want) of the internet.
In photoshop, resize it. 2.5 x the size you want usually works for me. So if I want a 2cm/0.8" keychain I make it 5cm/2". Print the resized picture.
Trace the picture on the shrink plastic.
Color this in.
Punch a hole in the top of the head.
Cut it out.
Bake it in the oven according to the packaging of the shrink plastic.
Put a keyring through the hole.