How hard is it to make a sten gun?

My Father owns a oil field equipment manufacturing company. Its a giant machine and fabrication shop, with everything including CNC and Plasma cutters. Obviously i'm not retarded, so i would never try to make a firearm, nor would he, but how hard would it be to construct a Sten Gun, hypothetically of course. He has the machine to rifle a barrel, and stamp steel, would it be possible to do so. AGAIN, I WOULDNT EVER TRY THIS! its just a hypothetical.