This paper describes the participatory design process of a new bricklayer’s trowel. The process consisted of five steps: 1) identifying ergonomic problems, 2) generating ideas for new design, 3) evaluation of five test models, 4) Field-study to compare to prototypes with the traditional trowel en 5) Implementation of the new trowel. Masonry workers were involved in all steps of the process, except during step 2 generating ideas for new design. This project resulted in three new products: a totally new designed trowel, a redesign of the sabre and a redesign of the traditional trowel. The traditional trowel was also redesigned. The reason for this was that the new designed trowel would hardly be accepted by the current generation masonry workers, because it needs another working technique. The redesigned trowel fits the requirements of the masonry workers and from an ergonomically point of view it is better than the traditional trowel, but worse than the new design.