This is the first prototype of some wheels I'm making. They're large omni-wheels designed to roll smoothly and without vibration, which can be a big problem with other omni-wheel designs. Unlike simpler wheels that use one or two layers of cylindrical outer wheels with gaps in between them, this design uses two different sizes of rounded wheels that fit inside each other to create a circular outer surface. I didn't invent this design, but I did draw up and make this wheel. As far as I know, no one manufactures them.
These are the spokes, each of which holds one and two-halves wheels. The small rollers fit in the middle of one spoke, and the big rollers fit in between adjacent spokes. This prototype was sintered out of nylon. The final version will probably be made out of aluminum and maybe some plastic to reduce weight. I have a lot of optimizing to do, but the final product should look fairly similar to the first picture above.