This article is focused on the design of demountable joints that have to meet high safety requirements. In total two snap-fit geometries were designed in two, respectively three modifications. These constructional solutions could be divided into two categories (easily deformable mounting elements and mounting elements deformable with difficulty). Several evaluating criteria were chosen. The most important ones were adequate strength, tightness and reliability of the resulting joint. Geometry of the snap-fit has to be also easy demouldable from the production tool and also manufacturability have to allow maximum user comfort during the assembly process. Optimization of snap-fit geometries was performed with utilize of numerical analysis and for the evaluation the prototypes created by 3D printing technology were used.