Open with an introduction on onomatopoeia's by showing an old clip of Batman. Here is one from youtube:
Next show them the art project, some examples can be found at Splish Splash Splatter Art
Then students can pick out 3 different colors of construction paper. (one for their background, one for their "zig zag" design, and one for the onomatopoeia word) You will also need newspaper.
Here is a close up of one of the examples:
There are a lot of different ways to create these, students will be able to use the paper to create their own onomatopoeia word designs!