If click on this post's title, you'll be taken to a webpage devoted to the AMT/Ertl Leif Ericson Galactic Cruiser model, later reissued in a glow-in-the-dark version known as the UFO Mystery Ship.
I had the UFO Mystery Ship. I received it as a Christmas present in the early to mid 70s, and I remember how thrilled I was; the spaceship had beautiful, futuristic lines, and it even had a hangar bay within which was a small mini-model of a bug-eyed scout ship. In fact, I interpreted this smaller vessel as the "UFO Mystery Ship." I imagined that the larger craft had come across the smaller, found it deserted, and hauled it into the hangar bay for examination. I used to concoct all sorts of weird reasons that the Mystery Ship's crew had vanished: they'd been eaten by a monster, they got locked out of the spaceship while on a spacewalk, they ran out of food, starved to death and decomposed, they were kidnapped by some more powerful alien, or most tantalizingly, they were still aboard the ship, only undetectable to the human astronauts. Sometimes the little scout ship would spring to life, shoot its way out of the hangar bay, and zip around the human ship, firing potshots at it. Usually, the aliens won, because they had the "UFO Mystery Ship." The name was so badass, so scary, that they just had to be more cooly competent and merciless than the humans.
It was a terrific model, and so a few days ago I did a blind web search hoping to learn a little more about it. I found out that the original Leif Erickson model was designed by none other than Matt Jeffries, the man who designed the USS Enterprise for Star Trek, and that the model came close to appearing in the animated followup to that show. Not only that, Larry Niven and Jerry Pournelle loved the original Leif Ericson model so much that they used it as the basis for the INSS McArthur from their novel The Mote in God's Eye. Looks like I wasn't the only one whose imagination was fired by that little box of plastic parts!