In recent years, extensive research in the HCI literature has explored interactive techniques for digital fabrication. However, little attention in this body of work has examined how to involve and guide human workers in fabricating larger-scale structures. We propose a novel model of crowdsourced fabrication, in which a large number of workers and volunteers are guided through the process of building a pre-designed structure. The process is facilitated by an intelligent construction space capable of guiding individual workers and coordinating the overall build process. More specifically, we explore the use of smartwatches, indoor location sensing, and instrumented construction materials to provide real-time guidance to workers, coordinated by a foreman engine that manages the overall build process. We report on a three day deployment of our system to construct a 12-tall bamboo pavilion with assistance from more than one hundred volunteer workers, and reflect on observations and feedback collected during the exhibit.