solid of contant width
thingiverse
When you have at least three of these items and position a plank on top, they will rotate freely just like they are sitting on standard bearings. Be certain to adjust the height settings in your slicing software if you plan to use all three simultaneously.
Download Model from thingiverse
With this file you will be able to print solid of contant width with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on solid of contant width.