That is one cool toy! I would have wanted something like that when I was their age. Heck, I want one now! That is some truly incredible work. Please keep us updated on any future projects you have, or any upgrades that are done to this machine. The only thing I would change would be the bucket. Most excavators have tines for loosening the dirt, like this:
Put some teeth or " tines " on the front of the bucket and then kind of clean up or consolidate the wiring. Automotive wire loom covering. It's going to snag on stuff the way it is right now. Neat toy. Nice job. Very inventive of you.