Menstrual pain is an embodied, unpredictable, and diverse lived experience. However, current menstrual tracking technologies mainly adopt medicalised and quantitative approaches, reducing pain to numerical data, concealing its organic and messy nature. To uncover the felt, lived experience of pain, we explored soft robotics as a tactile, dynamic medium. Through a series of material workshops, we designed MenstaRay, a novel artefact that mimics the temporality and fluctuations of menstrual pain. Findings from sensory interactions with MenstaRay show that soft robotic materials sensitise and enhance menstruators’ bodily awareness, supporting them in contextually recalling, introspecting, and reflecting on their pain experiences, and encouraging a sense of self-care, self-acceptance, and companionship toward menstrual pain. We frame MenstaRay’s dynamic entanglements with fluid bodily experiences as a meaningful material practice through a feminist lens, highlighting the creative potential of novel programmable interactions of knitted soft robotics to express nuanced pain characteristics, extending to other somatic experience design beyond menstruation.