Process of making hollow products, especially toys or pet products, and hollow products made with the process

A deformable ball comprising:

• a first hemispherical portion having a spherical outer surface and a spherical inner surface, with at least one opening interconnected therebetween, and a substantially flat mating surface, said substantially flat mating surface comprising an arcuate recess configured to form an inward facing step;
• a second hemispherical portion having a spherical outer surface and a spherical inner surface, with at least one opening interconnected therebetween, and a substantially flat mating surface, said substantially flat mating surface comprising an arcuate protrusion protruding therefrom being configured to form an outward facing step;
• wherein said inward facing step of said first hemispherical portion is configured to be engaged by, and be secured to, said outward facing step formed by said arcuate protrusion of said second hemispherical portion, in a form fitting relation;
• and
• wherein said first hemispherical portion comprises a first flange and a second flange, each configured to be substantially perpendicular to a plane formed at a split line between said first hemispherical portion and said second hemispherical portion and to protrude inwardly toward a central portion of said ball, and to enage said arcuate protrusion of said second hemispherical portion on an opposite side as said engagement of said arcuate protrusion with said inward facing step of said first hemispherical portion.