When enabling touch interactions on a deformable surface, the user is faced with a number of novel interaction challenges not present on firm surfaces. For example, the material used for the deformable surface can completely change the set of interactions that can be used. In addition, touching with one finger affects the overall shape of surface, and deformation for each touch individually can be hard. In this paper we discuss two prototype systems designed to enable us to study such challenges. We discuss how such challenges also present design opportunities to enhance interaction vocabulary of touch interactions on deformable surfaces and offer guidance to future designers of such interactions.