let's begin a list of needs for bearing variations
Slip Ring
We need bearings that can transmit electrical power & signals - the concept is to have electrical conductors lining some region of the bearing such that continuity passes from a fixed member to a rotating mated member. Perhaps the simplest starting point is to have a metal film (such as nickel strip) see Amazon inserted before the metal balls, contacting the balls & having a tab passing to the outside or the inside of a race.
The thin strip in the image below sits inside the outer race of the green bearing near the back. With the right geometry the strip can be placed by hand and compressed into place with the balls. Design will require adjusted clearances for the strip to be added.
CV Joint We need a family of CV joints for various sizes & torques. An initial design concept shown below:
The joint should be tested & characterized for approximate speed, torque, & range of angles so users can make a functional selection. It should have a prescribed method to mate successfully with various rod diameters. This design concept is uploaded as cv joint on grabcad
key design variants can be broken down here by intended use cases