The paper describes our work undertaken as part of a EU-funded collaborative project involving twelve partners from six European countries, aiming to provide a platform for the creation of tangible smart exhibits to enable heritage professionals to design and assemble physical artefacts enriched by digital content in a DIY manner. Our approach is grounded on principles of co-design, the broad participation of designers, developers and stakeholders into the process, and on a Do-It-Yourself philosophy to making and experimentation. Hands-on design and prototyping workshops are employed throughout the project to inform and shape development. The paper focuses on these co-design activities, wherein cultural heritage professionals (CHPs), designers and technologists work together in local and consortium-wide workshops to co-create the DIY platform. It presents the results of an investigation into the design thinking, practices, and processes of a particular set of users – cultural heritage professionals – who are involved in the design and realisation of cultural heritage exhibitions involving digital interactive technologies.