The chainsaw toy itself started out with some pretty impressive working internals including a rubberized chain "blade" and sound effects as well as a trigger with working safety. Merlocco did away with those niceties since he had to, but the end result is still a grisly and totally sweet way to experience one of the greatest first-person shooters of all time.
There's even a charmingly retro video showcase to give it a more realistic lilt, and even though it references the original release date for Doom (December 10th, 1993) it's still very impressive.