[Leo.G (Leo)]

Those multi-direction rollers definitely wouldn't be good rotating on a timber base as you've already decided, the wider units you've made up will be much better. Even were you to put a steel ring the roller would still eventually groove the steel depending on the thickness of the sheet and working with thick sheet steel is not easy, not light, far from simple to cut and would add significant cost.

Overall every bit of your construction is looking amazing. Did you work with timber as a trade/job or just an interest?