Oscillator!

"It's been four days! What is he doing out of the Academy?"

Jiu grumbled as she yanked the trolley that was carrying heavy Mecha Parts. There was livid rage on her face, but she didn't give up and kept on pulling the trolley. 

Eventually, she reached the studio where Professor was busy with the Welding Arc drone and with special glasses on his face. He was controlling the work of the drone with his utmost attention. Placing the trolley on one side, she collapsed on the floor to breathe heavily. 

But there was no fluctuation in the focus of the old man, on his signals the drone was working completely steadily. Not only was it hovering still in the air, but the extension of the pipe that was welding parts was also working with precision up to micros.