Video can be found here: https://www.youtube.com/watch?v=N2V0BuoXlf4

STL and Parametric Fusion 360 source files can be found here: https://bbprojects.technology/collections/stl-fusion-360-source-files/products/fully-3d-printable-bearing-files

Update 02/04/2021: A parametric version of this model has been added to the Fusion 360 source files. See link above.

These bearings are espacially designed for 3D-printing. These bearings don't use regular balls like other bearings but it uses specially designed for 3D-printing balls. This insures the most supple 3D-printable bearings with the least amount of play. The bearing prints in only one piece, fully assembled. You may have to wreck the balls a little lose after it has printed because the tolerances are very small. For the best result you can lubricate it with some grease. Hope you like it and can use it in your project. (results can depend on printer settings and type of 3D printer used).

I added a new 3D model of the small bearing to the file section called "homemade_printable_bearing_heavy_small_V3_easy_printable.stl" . With this model there is more space between the inner ring, the balls and the outer ring. This model should print more easy then the previous model but there will be more play between the inner and outer ring. This model is made for people who have trouble printing the first version. I'm sorry for this but I made the first version so my printer could print it without any problems. I didn't anticipate for the use of other printers. Hope this new model will be printable on most other 3D-printers.

dimensions bearings:
small bearing (V2 and V3): inner diameter = 12 mm
outer diameter = 40 mm
height = 12 mm

big bearing: inner diameter = 53 mm
outer diameter = 81 mm
height = 12 mm

Video can be found here: https://www.youtube.com/watch?v=N2V0BuoXlf4

Recommended tools:

3D-printer: https://www.banggood.com/Creality-3D-Ender-3-Pro-V-slot-Prusa-I3-DIY-3D-Printer-Kit-p-1346320.html?p=E01411629100201406T1&custlinkid=677427

Feel free to take a look at my other designs:

3D printable antweight battlebot: Bulldog: https://www.thingiverse.com/thing:4623536
SpaceX inspired edf rocket: https://www.thingiverse.com/thing:4606751
3D printed high torque servo/gearbox version 2: https://www.thingiverse.com/thing:4547703
UMC - Universal motion controller: https://www.thingiverse.com/thing:4245315
3D-printable Davinci catapult gift card: https://www.thingiverse.com/thing:4067668
Arduino controlled photogrammetry 3D-scanner: https://www.thingiverse.com/thing:3958326
Fully 3D-printable turntable: https://www.thingiverse.com/thing:3723618
RC FPV tank rover: https://www.thingiverse.com/thing:3587738
Fully 3D-printable wind-up car gift card: https://www.thingiverse.com/thing:3308710
3D-printable High torque servo/gear reduction: https://www.thingiverse.com/thing:3292860
'BOOM box' high voltage capacitor bank case: https://www.thingiverse.com/thing:2980012
Subby the interactive youtube subscriber robot: https://www.thingiverse.com/thing:2928254
robot hand || bionic hand prosthesis prototype: https://www.thingiverse.com/thing:2838239
3D-printable linear actuator: https://www.thingiverse.com/thing:2783959
Mini 3D-printable crossbow: https://www.thingiverse.com/thing:2710472
8 legged spider robot: https://www.thingiverse.com/thing:2470882
best 3D-printable bearing: https://www.thingiverse.com/thing:2349065

Have a nice day!