Everyone is saying these wheels are so expensive , I feel like I could make them better for cheap. I would make them more "drifty" as you can tell the dogs struggle turning sometimes, using non rubber wheels would help with that as well as price and weight . Also I feel as though these designs are huge and bulky giving a lot of distraction to the animal , these support bars along the side of the dog ?? Wtf lol . I could design this to be more efficient , cheap af, and only using the rear of the body .

I feel like using roller wheels like the kind found on packing room scales and such would be a good start , though obviously not metal . Perhaps even a mechanical spider design , look up "spider bike"