The power to have an innate understanding of mechanics with little or no study. Variation of Intuitive Aptitude.
The user can intuitively understand the operation of any mechanical device and subconsciously/effortlessly create a schematic in their mind. Many users are able to make complex devices or weapons out of mere scrap and "garbage".
Kevin Levin (Ben 10) is skilled at mechanics, able to invent alien weaponry, and rebuild entire cars.
Forge (Marvel Comics) possesses the ability to visually perceive "mechanical energy" and instinctively know and understand the potential and functional operations of any machine or technological device in his visual range.
With his incredible intelligence, Peter Parker/Spider-Man (Marvel Comics) designed most of his own equipment and weapons, most notably his Web-Shooters and Spider-Tracers.
Anthony "Tony" Stark/Iron Man (Marvel Comics) is always years ahead of the top inventors in his field.
Madison Jeffries/Box (Marvel Comics)
Chase Stein (Marvel Comics)
Mechanicles (Aladdin TV series)
Taotie (Kung Fu Panda: Legends of Awesomeness)
Gadget Hackwrench (Chip 'n Dale: Rescue Rangers)
Rotor the Walrus (Sonic SatAM/Archie's Sonic the Hedgehog)
Donatello (Teenage Mutant Ninja Turtles)
Dexter (Dexter's Laboratory)
Tech E. Coyote (Loonatics Unleashed)
Stewie Griffin (Family Guy)
Sokka (Avatar: The Last Airbender) has an almost natural aptitude for mechanics and technology.
Edd (Ed, Edd, n' Eddy) can invent some useful devices from junk, despite being a kid.
Tinker fairies (Disney Fairies), possess a natural mechanical intuition.
Ash Williams (The Evil Dead series) is an incredible inventor, able to create a fully-functional cybernetic hand from a metal gauntlet and gunpowder from referencing its elemental makeup in a chemistry book.
An accomplished mechanic, Dean Winchester (Supernatural) maintains his Impala, Baby in top condition once rebuilding the vehicle entirely from being severely disfigured and has maintained an intimate knowledge of automobiles and engines since childhood.
River Tam (Firefly/Serenity') is well-known as a child prodigy with extensive mechanical knowledge, among other talents.
Anthony "Tony" Stark/Iron Man (Marvel Cinematic Universe)
In addition to her magical powers, Willow Rosenberg (Buffy the Vampire Slayer) has enough knowledge of computers and robotics to repair and reprogram humanoid robots.
Antonio Garcia (Power Rangers Samurai) has sufficient knowledge of mechanics to repair Zords and reverse-engineer the Samurai Rangers' technology to create his own Morpher.
Skylar Adams (Alphas) is a Quantitative Aptitudinal capable to intuitively invent devices years ahead of their time.
Kelly (Misfits) displayed this at an advanced level, as shown being able to create rocket designs.
Link (The Legend of Zelda) often understands how advanced technological devices work, no matter how foreign they may seem to him.
Miles "Tails" Prower (Sonic the Hedgehog), a mechanical prodigy.
Doctor Eggman (Sonic the Hedgehog)
Wave the Swallow (Sonic the Hedgehog)
Otacon (Metal Gear Solid)
Professor E. Gadd (Super Mario)
Ratchet (Ratchet & Clank), like all other Lombaxes, is a natural with gadgets and technology, even building his own spaceship from scratch.
Bently (Sly Cooper) is extremely skilled with technology, upgrading his wheelchair with various weapons and gadgets.
Because of Sir Raleigh's evil and mad machines, he was able to build a storm machine and an entirely artificial island to loot ships of their valuables.
Arpeggio (Sly Cooper) studies led him to the works of the Italian Renaissance masters, whose notes and machinery designs served as a springboard for the sinister young genius. Eventually, he constructed a large blimp, which served as his home and base of operations.
Penelope (Sly Cooper) has multiple fields in technology, including piloting, using remote-controlled devices, and machinery.
Dr. M (Sly Cooper) is highly skilled in creating powerful machines.
Torbjörn (Overwatch) is a master mechanic and inventor.