This is the template I used for the boomerang. I uploaded a photo of the boomerang into Adobe Illustrator and created an outline of it that I then adjusted the size of and finally printed the template.

Since a boomerang is such a thin weapon I cut out two pieces of craft foam that I then glued together and sanded down the edges to get the look of a sharp blade edge.

Once the foam was shaped properly I heated up two pieces of worbla to put on the outsides of the foam. Then I sanded down the edges in order to get rid of any visible seams.

Its prime time! I used white gesso paint to prime the boomerang. I used about 10 layers of gesso total and sanded between each layer to make sure the boomerang was completely smooth so the paint would look as nice as possible.

The final step, painting. I used a light blue acrylic paint on the main part of the boomerang and a white paint on the edges to match how the weapon looked in the show. To truly finish it off I used a spray sealer to make sure no paint would chip off.