I made several sketches until I thought I had Gromit and Shaun with the correct proportions, then I traced those images on cardboard to make a template. One note, I made the small Gromits and Shauns small enough so that their eyes were the size of a hole punch. So instead of having to cut out a bunch of tiny white circles, I just used a hole punch to make the circles. I did sort of the same thing for the large Gromits and Shauns. I don't have any tools to make perfect circles, so I used a AA battery and traced the round part on a sheet of paper, and those were the eyes. Then I made the head proportional to the eyes.
I labeled all the food and desserts so people knew what they were eating. I made all the food labels with Gromit.