I do this lesson with my 3rd grade when we study Latin American art.
First we draw out our animals.
(Options are crocodile, wolf, crab, fish, sunshine, etc)
Use markers to make patterns on the inside.
Emphasize outlining multiple times.
Glue on black paper.
Use color copier paper in bright colors to make background strips.
I don't worry too much about them being the exact same size.