We describe the design process of an affective control toy, named SenToy, used to control a synthetic character in a computer game. SenToy allows players to influence the emotions of a synthetic character placed in FantasyA, a 3D virtual game. By expressing gestures associated with anger, fear, surprise, sadness and joy through SenToy, players influence the emotions of the character they control in the game. When designing SenToy we hypothesized that players would manipulate the toy to express emotions using a particular set of gestures. Those gestures were drawn from literature on how we express emotions through bodily movements and from emotion theories. To evaluate our idea we performed a Wizard Of Oz study [1]. The results of the study show that there are behaviours that players easily pick up for expressing emotions through the gestures with the toy, though not necessarily the ones extracted from literature. The study also provided some indication on what type of toy we should build, in particular, its look and feel.