The team produced over 30 sketches to come up with a design that fulfilled all requirements
The team searched for the perfect combination. “We have a big stock of materials we can test here, and we tested many different combinations of materials to find the exact hard-soft combination”. The selection process is a cycle of trial and error.
After extensive tests, they found what they were looking for: a firm but soft rubber for the bristles, and for the core, a material with the necessary stiffness and enough flexibility to ensure perfect performance of the product.