Tried to leave this comment on the target page where there is discussion of smoothing the ridged surface: There's another option for a smooth finish, or a fini

Tried to leave this comment on the target page where there is discussion of smoothing the ridged surface: There's another option for a smooth finish, or a finish with a different texture: stucco. The printer could easily create nubs, or short spines, at regular intervals that would act as supports for another coating. That coating could be sprayed concrete, or it could be stucco applied traditionally with a trowel. Masons can create a wide variety of surface textures quickly with a trowel. So the proposal here is to let the printer do the structural part, and details like cornices and dentillations, but leave the finish of broad surfaces to professionals with skills.