We present TomoTable—a research prototype of a position sensing device hidden inside an ordinary table. While the Human-Computer Interaction (HCI) field has extensively explored possibilities for spatially-aware multi-device interactions, the sensing methods that would enable such systems are still complex and hard to deploy in the wild. TomoTable presents a possibility of easily deployable invisible positional sensing that uses electrical capacitance tomography (ECT). Electrodes are embedded inside the table structure and provide accurate imaging of what is placed on the table. The entire system is invisible to the user. Objects can be identified based on their electrical properties. Our work creates opportunities for in-the-wild studies using multi-device systems. In this paper, we share the technical concept of TomoTable, preliminary insights on its use and perspectives for future studies.