In order for this part to work, the layer height needs to be quite low (0.1mm), so the spheres are round enough to make the joints easy to move. Supports are also required because the connection parts hang in the air. Also, I set the support angle quite low (40°), so the spheres stick to the build plate and don't come off. I printed with 3 perimeters and no infill and the parts turn out very strong.
I played around a bit with the diameters of the holes and for my setup it works fine like it is now, but if you have other tolerances it may not fit. If that's the case, feel free to contact me, than I can adjust the part to make it work for you.
Good luck with printing and have fun building a bionicle ;-)