John Lithgow & Cynthia Nixon in The Manhattan Project (1986)
Paul (Christopher Collet) is a bright boy. He excells in science and math and his curious mind is accompanied by a somewhat devious nature. John Matthewson (Lithgow) is a scientist working on high grade plutonium and trying to make time with Paul's mother. To that end, John invites Paul to visit his lab. Unfortunately, he's underestimated Paul's knowledge and understanding. In a move that's part protest, part prank, Paul and his friend Jenny (Nixon) steal some plutonium and Paul proceeds to make an atomic bomb with it for a science project. Will he win first prize... or even live to compete?
This film by Woody Allen collaborator Marshall Brickman was undoubtedly green lit because of the success of War Games (1983). It features the same archetypes and asks some of the same questions. The characters differ somewhat and have some compelling flaws. Some of the situations are a bit far fetched, but the whole thing holds together as entertainment. It's fun to see Cynthia Nixon as a teenager and look for Robert Sean Leonard in a small role.
This film is available on DVD, but can be hard to find online. Above is the trailer for it from Video Detective.
Obscurity factor: 9 (on DVD, hard to find otherwise, largely forgotten)