I recommend "Building a Mech at the Beginning, Iron Man saves the Empress". The protagonist of this city-city supernatural ability novel, Lin Tian, accidentally transmigrated to a world with weak technology. Fortunately, the system woke up at this time. He controlled the development technology of Iron Man, invented technology, and pushed forward the world's progress, allowing the world to increase its dimension and reward the host with eternal life. So this novel fits the plot where you want the protagonist to get a mech like Iron Man. I hope you like this fairy's recommendation. Muah ~😗