It's probably a good idea to make a model foil of your own ahead of time to show the students.
Students fold a sheet of notebook paper in half.
On the right side they list sevreal characteristics that describe themselves. Then they write the opposite of each of those characteristics on the other half of the paper. Students use aluminum foil to create a person, and they decorate that aluminum foil character to represent their foil. They may choose to represent several characteristics or just one. Then I list the opposite of each of these.