Perhaps the coolest concept of 3d printing is that you can make objects in one piece that would otherwise be impossible to make. This 4″ fully functional PLA ball bearing is a single print. The balls and inner race were all printed together intact which would be impossible using conventional manufacturing processes. I used this ball bearing in a turntable I made for my painting booth and it worked surprisingly well.
This ball bearing is printed in neon green PLA on my Dremel Idea Builder 3D printer. The file is from https://www.thingiverse.com/ stock printer settings were used and the file already included supports that are easy to break off and free the balls. While this 3d Printed ball bearing is not the smoothest running bearing by any means, it is however suitable for home projects such as a lazy susan, model building turntable, etc. I printed a snug fit flat base and a large round table top platform to be used as a turnable in my small paint booth.
Resolution for 3D Printing
My print was on the rough setting to save time. You would be able to produce a smoother running ball bearing by increasing your print resolution. And it can be scaled up or down to use it for a variety of other projects.
3d printing has really expanded the horizon in manufacturing. Designs that were once thought impossible to make can now easily be made in a printer on your kitchen table. With newer materials being developed almost daily including metals and woods, your creative options are endless. Everyone should have a printer and see where their creativity takes them.