We've shared the unglamorous early jobs of famous celebrities before, but some stars keep working on the passion projects long after they've become household names.
In fact, a few of them use their day jobs as inspiration for some very impressive inventions. There are a lot more patent holders in Hollywood than you realize. Check out 15 of the most famous examples:
1. Steve McQueen
The movie star didn't just play a daredevil on screen, he was a real life race car driver, and designed his own special bucket seat. Makes sense, since he did all his own car stunts in films like Bullitt and Le Mans.
2. James Cameron
The director helped design his own submarine, so it's no surprise he has some serious technical skills. To film the underwater scenes in The Abyss, he built and patented his own underwater camera propeller.
3. Mark Twain
If you love scrap-booking, thank Mark Twain. The Huckleberry Finn author loved the hobby so much he made his own books with adhesive already applied to the paged. Soon a whole line of Twain's books were selling across the country.
4. Gary Burghoff
Best-known as Radar from MASH, Burghoff became every fisherman's friend when he invented the Chum Magic in 1992. The device is filled with chum (fish parts), then floats on the water attracting nearby fish.
Think that's weird? You should see what Marlon Brando invented.