Making a robot toy was a huge undertaking. But now that it's done why not go off the pattern and make a new style that is compatible with the old? There's a reason this project was named Robot1.blend. Your own robot doesn't need to follow the strict alignment that this one did, that was just for tutorial purposes. Make a rounder robot based on a sphere or one that's all cubes. Make a robot with spikes and blades for hands. Just be sure to plan a flat surface for printing and remember the overhang.
If multiple robots are made to use the same sized connectors, then the parts can be mixed and matched between them. With only four different robots trading heads, bodies, arms, and legs there are a potential 256 different robot combinations that could come from them. That's a lot of play for a little bit of modeling.