The ball shaped cat toy - thing:1704548 - when printed with PLA and empty, bounced well. However it was fragile and easily broken. Here are two sturdier balls composed of 8 identical sections. In one the sections contain a distorted hexagon held in place by 4 rods; in the other a central point is connected to 6 rods. The balls were printed in PLA and in GP3D "FLEX" and bouncing comparisons made. OpenSCAD code is included.