The Slime People (1963)

Sculpted by Chris Choin and manufactured by Dimensional Designs. The overall green paint scheme was straightforward. The spear was base-coated with gloss black and airbrushed with alclad metallics. For the fabric at the spear head I took strands of supplied material and coated them with white glue, twisted the lengths into taught cords, and let dry. They were then looped around the spear head and superglued in place.

From Wikipedia:

The Slime People is a 1963 horror film directed by Robert Hutton. The film concerns a race of subterranean reptile-men (dubbed “slime people” due to their slime-covered skin) who create a wall of “solidified fog” around Los Angeles and proceed to invade the city. A pilot (portrayed by Robert Hutton) lands in Los Angeles after some difficulties in flight, only to find the city almost deserted. Later he encounters other survivors, including a scientist and his two daughters and the group does their best to halt the further invasion of the Slime People. The film was infamous for its extensive use of fog machines, with the fog becoming so thick towards the end that it is virtually impossible to see any of the actors.