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.

5. Marlon Brando

The Godfather actor got really into drums after retiring from acting. By the time he died in 2004, Brando had a number of drum patents including a special tool to tighten the instruments.

6. Francis Ford Coppola

There must have been something in the water on the set of The Godfather, because the film's director had a patent of his own. Coppola invented a t-shirt with a grid on the back, so you could ask someone to scratch a very specific itch for you. Pretty handy!

7. Jaime Lee Curtis

Curtis can do comedy, drama, and she's a great inventor. She patented a new kind of disposable diaper in 1987, with a built-in waterproof pocket full of baby wipes. The only reason she didn't license her invention is because no companies were making biodegradable diapers back in the late '80s, which she insisted on using.

8. Julie Newmar

Famous for playing Catwoman alongside Adam West's Batman, Newmar's form-fitting suit obviously gave her a few ideas. She invented what she calls "pantyhose with shaping band for cheeky derriere relief," which fit "between the wearer's buttocks to delineate the wearer's derriere in cheeky relief." Enough said!

9. Albert Einstein

You would expect a great physicist like Einstein to make some kind of high-tech invention, and while he did patent a number of things including a special refrigerator, he's most famous for his special blouse, which features "a central back panel extends from the yoke to the waistband."

Then again, Einstein was known for wearing the same thing everyday, so why should we trust his fashion sense?

10. Michael Jackson

The moonwalk was nothing but pure skill, but how did Jackson pull off his gravity-defying lean from the "Smooth Criminal" video? It turns out he used a special pair of floor-gripping boots he designed himself, which he later got a patent for.

11. Paula Abdul

This pint-sized pop star is only 4'9", so dragging around a mic stand taller than her body for a whole concert must have been exhausting. That's why she invented her own "dynamic" microphone, which sits on a concrete-filled base that wobbles but never falls over and slides easily.

Think that's impressive? A Hollywood actress invented Wi-Fi decades before the internet even existed.

12. Hedy Lamarr

The Austrian movie star lit up the screen in the '30s and '40s, but she was also an accomplished scientist. Her "secret communication system" used radio waves to remotely control devices, and was designed to steer torpedoes during WW2.

Lamarr and her colleagues were actually so ahead of their time that the patent expired before their technology could be built. Today, Wi-Fi internet and Bluetooth technology use the same principle as her devices, and Lamarr has earned a spot in the National Inventors Hall of Fame.

13. Bill Nye

"The Science Guy" put his knowledge to the test when he tried to redesign the ballet shoe, which has been basically the same for centuries. Nye's design added a special "toe box" and sleeve for added comfort, but it was never actually sold.

14. Abe Lincoln

Before he became our 16th president Lincoln was a bartender, a wrestler, a boxing referee and an inventor. He was piloting a boat down the Mississippi when he was inspired to create a giant bellows system to push boats off sand shoals.

So why wasn't Lincoln known as a great inventor? Because he wasn't. The size of his gizmo was so big it would have made boats sink deeper into sand barges.

15. Eddie Van Halen

The troubled rock star's signature style involves jamming with all 10 fingers on the guitar neck, which is a pain in the neck when your guitar is hanging too low. Eddie's solution was a folding prop on the guitar back, which holds the instrument up during his face-melting solos.

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