That design will be effective but take a lot of power to run. what are we talking for power source? It would be cheap I am guessing. Standard battery? If the bot were to have a spinning frame ring around it the frame would have to be fastened tight. If it weren't it would take a sledge hit and then fall off of the bot. Then its only defense would be a shell that dragged and shot sparks. Sounds kewl but one snag from a floor hazard and you can't move for a bit.
