We follow a person-centred, collaborative approach in the development of a set of innovative, interactive artefacts: the Spheres of Wellbeing , designed specifically for women with a dual diagnosis of learning disability and borderline personality disorder, who are living in a medium secure unit of a UK hospital. The women present a very vulnerable and difficult to treat client group due to their extremely challenging behaviours, complex needs and a persistent lack of motivation to engage in therapy. Simultaneously, they have a strong need for attention, care and positively experienced interactions. The paper presents the design and rationale of one of the Spheres: the Heartbeat Sphere , which is intended to encourage the women to practice mindfulness. Mindfulness practice is a vital component of Dialectical Behavioural Therapy; a specialist psychosocial treatment for their condition. Interactions with the Heartbeat Sphere are envisioned to complement their mindfulness skills practice and to enhance their mental wellbeing.