Arnie's arm in T2

OK in T2 Arnie cuts his arm up with a knife i know its not real but how do they do that ? 😕

put a large latex glove on and rip it off to reveal arnies real arm rapped in blue/green material. Im not an expert but i know my effects

As far as I know no blue or green material was used. Arnolds real arm was put behind his back (or something like that to hide it) and a fake arm (the endo arm) was attached and covered to look real.

It looked like plastic to me