M.O.N.T.E.

The "killer robot" built by the guys was called M.O.N.T.E., which stands for Mobile Omnidirectional Neutralization and Termination Eradicator. It's a remote controlled device, quite heavy, with a buzz saw attached to the front. M.O.N.T.E. was destroyed by Barry Kripke's massive, fire-breathing robot in a one-on-one "street fight" which makes an apperance during The Killer Robot Instability episode.

M.O.N.T.E. is born!
This happens in the beginning of the episode, where Howard is making the finishing touches on the gang's killer robot. Video:Big Bang Theory MONTE

M.O.N.T.E. vs. Krippler
Kripke was able to convince the gang to face his robot, Krippler. Sheldon refuse to back down against one of his bullies threats and continues to fight on. Video:M.O.N.T.E. Vs. Krippler