As a companion to an earlier post that featured some of Marvel's characters getting makeovers or upgrades in their abilities or accessories, following are a few more examples where our heroes either felt a little something extra was needed in their crime-fighting arsenal or were forced to improvise due to unforeseen circumstances.
As far as improvisation goes, you can't have a much better example than Reed Richards, who probably scavenged his entire spare parts vault in order to come up with believable substitutes for the Fantastic Four's abilities when radiation from a bomb explosion caused them to lose their powers. Reed is no Tony Stark, of course, but he does pretty well in a pinch--though his efforts appear futile.
Reed does considerably better in the Thing's case when Ben Grimm reverted to his human form following a battle with the Hulk and needed a way to remain part of the group. The answer: a custom-made exoskeleton that gives Ben nearly the power of the Thing but also allows him to slip into something more comfortable when he wishes--i.e., his humanity.
Otherwise, given their formidable powers, the FF are pretty self-sufficient when it comes to tackling their foes, needing only their resolve and their resourcefulness to see a crisis through. But thanks to Dr. Doom, who isn't exactly lacking in resourcefulness himself, Reed came to the conclusion that he and his teammates needed something more than their powers to defeat their foe. And so there came a day when the Fantastic Four charged into battle--I am not making this up--donning flak jackets and packing heat.
(Somewhere, the man called Cable is feeling validated.)
Over in the Avengers, the Black Knight--who has no super-power to speak of but became an Avenger by pulling their fat out of the fire against Kang--is no longer in possession of his winged steed, Aragorn, and so tinkers a bit with technology acquired from a previous mission to produce, voilà, Aragorn 2.0.
Later, there's also the matter of finding a substitute for his cursed ebony sword, and in so doing the man demonstrates that he's a total Star Wars geek.
As for Captain America, he too must resort to technology when his shield is lost at the bottom of the ocean and his substitute shield has proven to be nowhere near as resilient. Thanks to Sharon Carter, a piece of hardware from the past is dusted off and given a new, familiar look that will fulfill Cap's need for a weapon that can handle both his offense and defense needs.
The mighty Thor has also been known to employ ways to both protect himself and to enhance his own power when necessary. An example of the former would be the suit of specially forged armor he created as a means to offset a curse placed upon him by the death-goddess, Hela (you can see it in action during his rematch with the Celestials). But there's also his belt of strength, first seen in a 1963 story and arriving by special delivery from Asgard.
The belt appears again fifteen years later (our time), when Loki once again has an edge over Thor, and it's Thor this time who summons the belt to compensate.
Like other heroes who have given themselves an upgrade, the Son of Satan would practically reinvent himself when he debuts his new look in order to accompany the Avengers on a mission, trading in his "psycho-sensitive trident" for--what is that thing he's carrying now, his training trident from when he was a child?--and providing us also with a new identity, as the man known as Hellstorm.
Finally, Spider-Man receives an upgrade, courtesy of Tony Stark, that for all intents and purposes provides us with a mobile-friendly version of the web-spinner that these days would be just begging to be hacked into.
("Okay, Mike, we're in! Now, make him crawl up that water tower backwards!")