This is a parametric boomerang model made in Onshape.

"Parametric" means that in the model, there are variables for the elbow angle, the arm lengths, thickness, etc., which can be manipulated and the model updates accordingly. This allows you to generate an infinite number of different boomerang shapes.

I've printed and tested the basic shape and it flies well with some weight added (see my makes of this model). If you change the parameters, results may vary. Don't go too light on the infill, as the model will be too light and too floppy to work well. 50% seems to be just about right for me.

The Onshape model can be found here:

https://cad.onshape.com/documents/f4fc462cbce27d8bfdbc5d95/w/089a8c7db69016406335e7b5/e/eb06c4bf9a91bfaa64e0f7a9

I really recommend not just getting the STL, but playing around with the Onshape model and seeing what you can come up with.

Edit: The omega.stl is a different shape that is derived from the same model. I just straightened the wings a little and increased the radius of the elbow section.