Printed at about 150x150 millimeters and 9 grams, this is truly a pocket-sized boomerang. Depending on tuning, it will have a range of about 8 - 15 meters, so it should be fine for backyard use, if your backyard is large enough.

I don't see any reason, though, why it shouldn't work just as well if printed at a larger scale. It will probably have a larger range then.

Even at this tiny size and 9 grams, it can take moderate winds; just make sure to tune it for a low flight (bend wings downwards a little) to avoid hover.

How I Designed This

Designed in Blender 2.8. Have a look at the .blend file to see how this model is made.

I used the HardOps addon to simplify the creation of the symmetric shape, but it can be done just as easily in vanilla Blender, it just takes a couple more mouse clicks.

The print shown here has too few top layers (6 at .08 mm layer height), so the "knurling" of the top is the infill ghosting through. Two layers more would have fixed that.