Involving and engaging people with learning disabilities on issues relating to their mental wellbeing can bechallenging. This research explores how participatory design techniques and principles can be used to engagepeople with learning disabilities in designing technological solutions relevant to them that could monitorand aid their mental wellbeing. Specifically, we explore methods used in a series of co-design workshopsto engage people with learning disabilities in the use of tangible interfaces for mental wellbeing. A varietyof designs, sensors and interventions were explored during the workshops resulting in the development ofmultiple mental wellbeing interfaces. Furthermore, data collection trials using the developed interfaces havedemonstrated the potential to collect real-world labelled data that can be used to train machine learningclassifiers. The co-design approach adopted for the design of the mental wellbeing tangible interfaces ensuredthat effective and suitable devices have been developed