An automated fabrication system is provided that utilizes electromagnetism to manipulate and/or sense the location of raw materials on a platform. Tools located around said platform may be utilized to fabricate a predetermined structure out of the raw materials. Tags that can be electromagnetically manipulated and sensed may be placed on passive raw materials. Structures fabricated from such a system may be, for example, a roof truss. Additionally, the fabrication system may be mobilized by way of a truck such that structures may be built on-site.