<p>This paper presents a robotic workflow for the prefabrication of customised free-form earthen building components using intrusion earth additive manufacturing (IEAM). IEAM is a particle-bed fabrication method in which a robotically extruded earth paste is intruded and compacted into a bed of loose mineral aggregates to create load-bearing, geometrically complex earthen elements. Unlike conventional industrial building materials, earthen components are inherently circular: at the end of their service life, they can be dissolved with water and remanufactured, eliminating construction waste. The robotic process is layer-based and fully automated: an earth binder is deposited directly into an aggregate bed, followed by the controlled distribution of loose aggregates with a recoater and their compaction using a stamping tool, all executed via a multipurpose end-effector. The proposed workflow establishes a coherent prefabrication process and illustrates how IEAM can be integrated into contemporary construction practices. To validate the method, a prototype robotic IEAM setup was used to prefabricate a full-scale wall segment composed of six free-form earthen components using an earthen binder and crushed brick aggregates, demonstrating the feasibility of the design-to-fabrication workflow, fabrication accuracy, and the handling and assembly of large-scale structural elements. Building on these results, the paper outlines a vision for compact robotic field factories capable of operating directly on or near construction sites. Such systems could utilise processed excavated earth as the binder and sorted, crushed demolition debris as the coarse aggregate, enabling local, circular, low-carbon building component production. By relocating fabrication closer to the point of use, this approach could reduce transport, shorten supply chains, and strengthen the viability of automated regenerative construction practices.</p>