In this study, a hardware configuration for reducing the size of a scent projector is proposed, and its performance is examined using a prototype system. A scent projector is a system that delivers a small amount of scented air to the user's nose by channeling the scent through a vortex ring. A projector enables scents to be presented locally in time and space without requiring the user to wear any special apparatus. Such localization is important when scents are presented synchronously with other sensory stimuli. However, scent projectors make use of so-called “air cannons” that usually have significant volume, making their size a major drawback. To solve this problem, we examined the principal parameters that affect the performance of a scent projector, and found that the inner volume of the air cannon does not seriously affect the range of a vortex ring. Based on this analysis, we designed a flat-shaped scent projector that has zero volume in the idle state and built a prototype system. Our prototype performed almost as well as existing scent projectors with larger volume.