In the UK, bowel cancer is the second largest cancer killer. Diagnosing people earlier can save lives but demand for endoscopies is increasing and this can put pressure on waiting times. To address this challenge, an endoscopy unit in North East England decided to improve their facilities to increase capacity and create environments that improve the experience of users. This presented a significant opportunity for step change improvement but also a problem in terms of creating designs that meet user requirements whilst addressing structural or space constraints. The Lean design process known as '3P' (standing for the production preparation process) was utilised as a participative design strategy to engage stakeholders in the design of the new department. This involved a time-out workshop (or 3P event) in which Lean and participative design tools were utilised to create an innovative design based on 'point of delivery' (POD) principles. The team created a design that demonstrated an increase in treatment room capacity by 25% and bed capacity by 70% whilst reducing travel distance for patients by 25.8% and staff by 27.1%. This was achieved with an increase in available space of only 13%. The Lean 3P method provided a structured approach for corporate and clinical staff to work together with patient representatives as cross-functional teams. This participative approach facilitated communication and learning between stakeholders about care processes and personal preferences. Lean 3P therefore appears to be a promising approach to improving the healthcare facilities design process to meet user requirements.