In this paper, we explore a novel idea of theory instruments: tangible artifacts that encourage participatory design practitioners in the industry to reflect on interactions with technological devices in the light of a particular theory. Our Actor-Network Rings instrument is based on Actor-Network Theory as this is one way to challenge taken-for-granted assumptions about what effects digitalization have on product users and their lives. The instrument consists of wooden rings, wooden balls, clothespins, and magnets. By adding wooden clothespins as actors and plastic ones as actants on wooden network rings, upholding a wooden ball becomes visible and even tangible as a program of action. Shifting or removing clothespins visualizes concepts of imaginary substitution and delegation. We analyze two cases of how designers and design researchers in companies use the instrument to investigate dilemmas of people and technology. With transcripts from video documentation and hand-drawn visualizations, we show that the instrument elicits broader insights into the dilemmas and even opens ideas for future scenarios. We argue that there is a potential for developing such theory instruments that, in a playful manner, offer fundamental theory perspectives to inform understandings of digitalization.