Ferrocement, with the addition of 3D printed, plastic forms.
The difficulty of ferrocement lies in creating forms for complex geometries. The challenge is a tradeoff between form accuracy - and minimum cement thickness. The more precise a form, the thinner the ferrocement could be. Placing metal mesh and fixing it to wood or other forms is the time-intensive part.
This process can be simplified greatly by using 3D printed forms which accept both the metal lath or mesh, and provide a container for the cement. This way, the automated 3D printer does the difficult work. This requires 3d printers that can print on the scale of construction modules, including access to low cost filament feedstock, and high temperature print chambers to enable printing with any type of material.