In the process of making a hollow product, especially a deformable toy ball, two halves made from on elastomeric material, a thermoplastic material, rubber, a blend of rubbers, or a thermoplastic elastomer are formed by injection molding with mating edges that engage with each other when the halves are assembled to form the product. The edge of one of the two halves is advantageously formed with a recess centered in the edge, in which a flange formed on the edge of the other of the two halves engages to provide a form-fitting connection between the two halves. The opposing edges are then bonded with each other by fusion or melting or by an adhesive applied to at least one of the edges prior to assembling the halves together. A deformable ball produced by the process is also described.