As a side note, and JFYI, in a number of structures (designed for it) rebar can be partially or totally replaced by steel (or other high strength material) fibers.

More or less the whole idea of concrete stuctures is to use a composite material where the steel (rebar) is used for traction (and shear) and the concrete for compression resistance. (as opposed to other materials such as wood that has resistance to both traction and compression (besides shear) forces.

A fiber-reinforced concrete can (as said in some cases) be considered a form of reinforced (rebar) concrete at a smaller scale and with "fuzzy" (or "diffused") distribution of the reinforcement.

Domes and similar "thin" structures are very suitable for being made with fiber reinforced concrete.

You don't need to substitute rebar. You can add rebar manually or have a second attachment to the arm insert rebar at opportune moments.