It’s Alive! (1968)

A loony farmer (Billy Thurman) finds a prehistoric monster hiding in a cavern on his land. To feed the monster, the farmer kidnaps three people. The three desperately try to escape and finally, one of them succeeds. Also stars Tommy Kirk and Shirley Bonne.

The ping-pong-eyed monster costume is the same costume that was used for the monster from Creature Of Destruction, also available here at Rare Movie Collector.