Abstract: As an input device, fabric holds potential benefits for three dimensional (3D) interaction in the domain of surface design, which includes designing objects from clothing to metalwork. To investigate these benefits, we conducted an exploratory study of different users' natural interactions with fabric. During this study, we instructed users to communicate various shapes and surfaces of varying complexity. A prevailing way of communicating shapes proved to be an in-the-air sketch metaphor. Based on this result, we proposed and implemented a system supporting three in-the-air sketch-based input devices: a point, a flexible curve, and a flexible surface. A preliminary feasibility study found that users successfully sketched objects and scenes despite the influence of tracking issues, suggesting lessons learned and relevant constraints for such systems in future work.