Virtual reality systems often make use of spatially tracked handheld props in the form of controllers or specialized objects to add realism and interaction. Tracking these objects today relies on the use of expensive, bulky, and power-consuming trackers that must be attached to an object. We propose a passive tracking technique that works with existing low-cost, off-the-shelf optical tracking components and is capable of turning any object into a tracked virtual reality prop. Our method utilizes paper-thin retro-reflective markers that can be placed in any free-form on everyday objects. The proof-of-concept prototype acts as a simple add-on for an existing tracking system and requires only a minimal amount of compute overhead. We demonstrate that our method allows bringing physical real-world objects to virtual worlds with ease, and provides an object identification technique using patterned retro-reflective markers.