No supporting structure needed.

Creating Gyro Air It had it´s challenges, but after 5 prototypes and a lot of PLA, I arrived at the final model. I don't like supports, so I made every form nice and round.

For better results I recommend printing the Gyro Air at it's original size of 10cms. I have also tested it at 80% and i think it's the limit. Printing it too small will make the circles too thin and it might break.
I printed the final object with a 0.25mm layer size.
Once printed snap the conical nipples into place beginning from the smallest working your way up to the biggest.
You can add a drop of oil to the joints so the spheres rotate freely.