Ahh! That clarifys it a lot! What about short cove and bead strips placed vertically, around the circumference, rather than bent into hoops? Much easier to build, I should think. If you worked with thicker strips, say 3/8" -1/2" mebbe, the wheel would have signifigant strength. You could even rout a small guide notch into the outer side, prior to assembly, for the roller wheels.
The outer rims could be as simple as very thin plywood.