The fake monster O'Bryan creates is a huge orange humanoid with pointy ears.
In one humorous sequence, the Colossus terrifies a group of Beatniks.
The Colossus last appeared in issue #14 (February 1961). Colossus, Bob O'Bryan, Diane Cummings and Grant Marshall all appear next in Astonishing Tales (Marvel, 1970 series) #21 (December 1973).
George Olshevsky's Marvel Comics Index credits Stan Lee as sole writer. Story is pages 3-7, 10 of comic (pages of story numbered 1 to 6).