Class 2: Robot Monster. I may be one of the few people alive who actually watched this in a movie theater. The "monster" was an actor in a gorilla suit and wearing a diver's helmet with TV rabbit ears glued to it! I believe they hired him because he was able to supply the costume. This vies with "Plan Nine for Earth" as the all time worst Sci Fi movie.
That would be "Plan 9 from Outer Space." You can see that movie being made in the Tim Burton movie, "Ed Wood!"
That's a wonderful movie.
Mark