A boomerang that I modeled after one that I made from wood.
This is similar to thing:28603, it only has sharper airfoils and I took care that it is about 20 x 20 units in the STL file, which scales easily to the 20cm x 20cm space that the 3D printing company I use offers.
Note for Lefties: You'll need a mirror image of the boomerang. A mirrored copy is included in the downloadable files.
Will work best if scaled to between 20 x 20 and 30 x 30 centimeters and a thickness of about 3.5 to 4.5 millimeters.
Mine has a wingspan of 215 mm and is 3.5 mm thick.
You can greatly enhance wind stability, spin retention, and distance by taping a small coin to the first arm as shown in the photo.