Affective touch, which involves slow, gentle mechanical stimulation of the skin, is drawing interest from the Human-Computer Interaction community in recent years. Stroking, the most common form of affective touch, is strongly related to emotional responses and has been proven beneficial for interventing and mitigating anxiety. This has led to a growing need for developing wearable stroking devices. In our study, we first presented a custom-built forearm-worn interface. We then explored the design parameters for stroking devices, focusing on 2 factors: (1) the form factors (shape / material) of the end effector contacted directly with the skin, and (2) the stroking distance, respectively.