I think a chain is possible and practical from presently available CNT = carbon nano tubes, and a little binder, such as epoxy resin. It would be about eight times stronger than quality steel chain by weight, but less than twice as strong by volume, so there would likely be few who would want to pay the premium price. Large premium at first as considerable R and D would be necessary to optimise CNT chain, The R and D would need to be repeated, when and if, better CNT becomes available. Has anyone seen any fiber glass chain or carbon fiber chain which would be almost as strong as CNT chain we can make at present?   Neil

I agree, and likely manufacturers are working hard to get the price down where terrestrial applications would be attractive. Really cheap CNT might sell a millon tons the first year. Carbon is low cost, so we may find a way to make cheap CNT.