Make a Boomerang that actually comes back!

Step 6 How do I shape the edges?

You will shape the edges with lots of sanding. Palm sanders and orbital sanders work well for this, however it can take some time. A belt/disk sander makes sanding easier and faster. The machine in the picture is my favorite machine to use for this. It has a gage for the angles and takes material of quickly but not so fast that you take off to much.
Follow any power sanding with hand sanding.
Round the front edge just slightly, it will make it easier to throw.