This is our off season project. This gave the students a chance to cut, grind and weld steel. We had it sandblasted and powder coated. We can remove the tool box and drop the frame down 9 inches for local demostrations where we don’t need all the weight.
Very Nice! 
My team (2395-Ninja Munkees) actually made a motorized robot cart during last years build season. But unfortunately, we didn’t make any room for good sized tool box like you did. 
We are only able to fit a pretty small tool box on ours.
We can actually put two tool boxes (back to back) along with a cordless drill and a couple of batteries on the cart.