I started this project from this concept I painted here:
Volt is basically a living ball of energy that powers his mechanical suit to thrive in various terrains. So this design is all-purpose and humanoid. I started with his real body:
Once I had that I moved into blocking out the mech in Maya then brought that into Zbrush:
Then I pushed and sculpted that around a little until I started getting into trouble with his shoulders and connecting pieces:
Final result after rebuilding the topology and adding details:
And then retopologized and semi-rigged/posed in Maya: