Understanding the physics behind an elastic sphere

So far the only issue seems to be the balloon latex catches on the metal I was wrong, it's actually getting caught between the bearing and it's metal encasing ( when I put pressure down) of the roller bearings. It does stick to the metal exterior but only on the exterior rollers. If the latex can't expand to hang over the roller then it won't be an issue.
I ordered some metal bearing balls to test as well, though that would require a special metal bowl to allow them to roll in place, or maybe something to coat the ball and metal like surfboard wax (we used that on our sliding metal door when I was a kid).
First I used just a regular balloon, filled it with sand and then blew some air into it. It was expanding too much so I doubled up on the balloons.
Filling the double balloon with 1/3 and 2/3 air seems to be a good combination so far. The latex can still expand slightly and the sand has enough room to roll over itself and stay on the bottom.
I honestly won't be able to properly test this until I have a bigger sphere to work with. Unfortunately that will require a lot more bearings, which are fairly expensive in mass.
 
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So for anyone curious, ball bearings by themselves work fantastically, far better than the roller ball bearings. They rotate much more freely, and can handle weight much better.
I'm moving on to larger scale testing, large enough for walking with full weight, albeit with small steps.
The problem with ball bearings is trying to keep them in one spot. I figure once I can fill the surface with ball bearings so they don't have space to move it should be fine.
The other problem will be to keep the sphere in a central spot.
Eventually I'll make some sort of encasing like the roller ball bearings have, where it just comes over the edge of where the sphere expands outwards to the point where it keeps it from moving laterally.

Anyone have any knowledge on a material that won't provide the sphere with friction, or at least very little?
 

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