In Avengers: Endgame, Tony is able to make
his own Infinity Gauntlet
how was he able to as, in Avengers: Infinity War
Thanos went all the way to Nidavellir to get his, and needed dwarves and magic to build his
How was Tony able to build this using only human technology?
Tony has spent quite some time studying two Infinity Stones in Avengers and Age of Ultron, so he already has some familiarity with them.
In addition, a day or two previously he invented a wrist-sized device that enables successful time travel in his spare hours between lunch and his young daughter finally going to bed. He's a smart guy.
As Thor explains to MCU lynchpin Jane Foster in his first movie, magic is just sufficiently-advanced science. Tony, presumably with Bruce and Rocket's help, figured out how to make an Infinity Gauntlet from first principles.
There's no indication that Thanos needed Dwarven magic and the forge at Nidavellir to create an Infinity Gauntlet that works. What he actually needed was the knowledge that the dwarves possessed.
Thor: Eitri, this isn't about your hands. Every weapon you've designed, every axe, hammer, sword...It's all inside your head. Now I know all hope feels lost. Trust me, I know. But together, you and I, we can kill Thanos.
Avengers: Infinity War
Tony possesses the same knowledge to create an Infinity Gauntlet because he has spent time studying the Infinity Stones to quite a complex level. He has studied the Mind Stone and the Space Stone over the course of the movies.
He also has the help of Dr. Hulk who has previously studied the Infinity Stones with Tony and Rocket who is incredibly intelligent and has come into contact with the Stones before even wielding the Power Stone with the Guardians of the Galaxy.
By this point in the movie, they would have had the original available to reverse engineer.
While Thanos destroyed the Infinity stones he did not destroy the gauntlet. Presumably, Stark recovered it after Thor killed Thanos.
Collectively, the Avengers Engineering team all had experience with the Infinity stones (Tony, Bruce, Rocket, Nebula)
It's even likely that Nebula may have known how the original was made.
oh and don't forget that "magic is just sufficiently-advanced science"
Let's see. He did have a couple of resources at his disposal. Mainly,
We're talking about the guy who did build the equivalent of the Asgardian destroyer (minus the indestructible metal and face-beam), without any magic involved.
As others have said... he's had time to study the stones.. but, more importantly, things that HOUSE the stones.
He's been able to study the cube that contains a stone He's been able to study the "glow stick of destiny" (Loki's staff) that holds a stone He was probably studying Vision to see how he could hold a stone in his head
While Tony used to be an engineer, in the latest movies they've been showing him as a Data Scientist. He's created neural nets / AI's that grind though vast amounts of machine learning / deep learning. The way this works is you set up inputs, nodes and an output / goal. The nodes (could be thousands.. millions) are all decision points. Then you fire off the inputs (what you know about the stones, what they've been in, how they react to things.. eg: some stones seem ok to hold by hand by a human, like the soul stone, while others consume the user unless they're sufficiently powerful enough) you send all that through the machine learning / deep learning algorithms and then yuo.. wait... until it spits out an answer that best matches your goal.
The trick with machine learning / deep learning algorithms is that they're shooting for statistical probabilities. You want models that are 100% accurate. But, sometimes you only get 90% or less.. predicitive modelling, etc. (eg: in data sci they had us run genetics from known cancer patients and mash up against unknown patients. You create a training data used to train your model, and a test data set to test it to see how accurate it is. For really complex stuff, you're going to be at less then 100% accuracy / prediction.)
Tony gets baked at the end of the movie, which means his gauntlet was flawed.. it worked to do the task, but didn't protect him from the blowback of power. But, it protected him amazingly well seeing as how it let a mere human use all 6 tones to accomplish greatness and still be alive after-the-fact to live long enough to know they won. He was there and saw how Thanos got burned from the backlash of the gauntlet. So, he probably knew that he had to factor in the power of the stones. But, when time is a factor, you can only run so many models for so long before you have to go "you know what, it's not 100% fool-proof, but it's the best we got." If he had more time, he might have been able to make a guantlet that surpassed even the Dwarves. But, with limited technology and limited time.. he did the best he could with what he had. And, it was enough to enable a human being to weild all 6 stones and snap his fingers. It killed him, but that's still ludicriously impressive... seeing as how the power stone alone almost fried Quill in the first Guardians movie.. and he was half-cosmic.
tl;dr ... Tony is the ultimate geek in these movies, from engineer to data scientist, and he's got AI's and deep learning at his disposal.
If we can (in real life) have IBM's Watson beating the pants off of contestants on Jeopardy, then imagine the kind of AI tech a super-rich tech genius super-hero guy must have to help him invent toys.
One point that the other answers don't cover is the fact that the point of Thanos' gauntlet wasn't just to "harness" the stones -- if nothing else, the first Guardians of the Galaxy movie shows that a big hammer can do the trick in a pinch -- but also to survive using them.
If you compare the amount of side effects and sheer damage inflicted on the wielder of the Infinity Gauntlet compared to the one Tony bashed together in his lab, you'll note that the latter caused significantly more bleedover, even to Thanos.
I disagree with all the statements RE Tony only needing the knowledge to create one.
If he did, then you're all saying he has the power to create hundreds of Stormbreakers and Mjolnir. Thanos went through the trouble to Nidavellir to create the Infinity Gauntlet because of - the materials used, the dying star used, and the profession of the Dwarves, otherwise he could've gone anywhere else (quote from Rocket to Stark "you're only a genius on Earth").
And let's clear something up. The problem here isn't making something that can 'hold' all the stones together, it's making a device that could 'harness' (i.e, make use of) these stones.
So I think the only possible explanation here, is if they took Thanos' gauntlet and Tony reverse-engineered it to create it. But even this I dislike, as it wasn't even shown in the movie that the team took it with them.
The one thing that everyone is forgetting - by this point in the movie he has already done it once, and in a way that can change size to fit whomever puts it on.
Given that, he's probably used something similar to what his current suit is made out of, so the "how" is already part of what he's wearing given how he controls it via the implants he added several movies ago.
The original "how" he could do it for the first one, see the other answers :-)
(Answer deliberately vague so no need for spoiler tags - several other answers could definitely do with them though...)
