Wow, I finished three models in one weekend!
This is Challenge 142, the ship from "It! The Terror from Beyond Space"
It's from Larson Designs, who now owns the old. Lunar Models resin and vacuform kits.
The ship design originated with Chesley Bonestell's design for the "Luna", for "Destination Moon", but a different ship design was used in the movie. It was used in "Flight to Mars" and finally, in "It! The Terror from Beyond Space"
The Bonestell "Luna" and the version in "Flight to Mars" were designed to be 140ft/42.7m long. In "It!" The Challenge 142 was "rescaled" to be twice the size. So this model built as the Challenge 142 would be in 1/350 scale. As the "Luna" or "Mars-1" it would be 1/175 scale.
I added the many airlocks the two windows and the control surfaces, using the drawings in "The Spaceship Handbook" to draw the decals. The kit was an OK build; clearly a garage kit, it required some cleanup.
I see from the screen grab below that I missed one set of airlocks: