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Yah, I've seen those. I could make those work if the wheels
were rubber. It has to travel across textured ceramic tile
so steel is out.

I'm pretty sure you're not going to find very much. Even the hooded casters
had an axel through the ball. Roller balls as in the last url I gave you
only work because the encased steel ball is able to withstand the pressures
and friction. A rubber encased ball wouldn't stand up to that kind of abuse
for very long, at least not being used as a caster holding whatever weight
was put on them. I have seen entirely plastic units, but only for something
light as in a roller balls on something like a grocery outfeed table.