In groups of 3 make a letter of the alphabet.
Show them to one another and try to guess them.
Choose one group of 3 in turn and the rest of the group brainstorm out loud any words, shapes images or stories they see.
Each group create a short scene using the ideas given with their shape as a component of it.
You can join groups (shapes) together to create a short scene where they either go together or offer a contrast.
Comment: I did this recently in a school with primary children and it worked a treat. It is something that they had a lot of fun doing without having to think too much, but it opened up a whole load of ideas when they started to look at one anothers shapes.