Isn't there a summoner archetype that lets you "wear" your eidolon? Design your eidolon to be Iron Man's armor.
You'll need to be able to fly and cast energy rays. Depending on if you are pursuing the comic book or film version of iron man, there are other spells, items that would be useful.
Crafting flying magic armor would work for any armor wearing class. Customize the armor to allow you to insert wands into the arms of the armor and cast the wand spells. You'll need enough ranks in Use Magic Device to pull this off.
To really be "iron man" you will need your AC to be off the charts. That's his main schtick. So anything that boosts AC would be good.
Just for a different option (since the easy and more reasonable options have been mentioned)...
Check out Ultimate Magic, Mastering Magic, Building and Modifying Constructs (link).
Specifically, the Construct Armor complex modification. Build a golem, wear it like armor.
Costs a boatload of cash to pull this off. Have to be pretty smart (caster) and freaking rich (the armor modification is 35,000gp alone). Pretty much exactly what a Golarion-ified Tony Stark would be.
Since it takes high caster level to get a decent metal golem, and the money and time involved with this, I'd say one of the other options is a better route.
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Although I could see a high level commoner who's only "ability" is some decent skills focus, the unique ability to get Master Craftsman to work with golem creation, and the unique background of "a boatload of sustainable wealth", being something almost playable (although potentially rife with abusable options).
Might make a better NPC...
*Edit* Pah. Ninja'd because I spent too long writing the post, heh.
Only if it's a level of Spell Slinger. ;)
Another possibility: Your GM is using Psionics Unleashed; see if he's also using Psionics Expanded. If so, take a look at the aegis.
magus or summoner.
If 3pp are legal look at the Tome of Secrets Artificer its all about making spells into tech.
The Aegis from Dreamscarred Press's Psionics Expanded: Unlimited Possibilities is a really good option for Iron Man, perhaps multi-classing with Soulbolt archetype for the Soulknife from Psionics Expanded: Find the Mark. There's even a prestige class for a multi-class Aegis/Soulknife (which should probably work with the Soulbolt option, but I'm not sure).
You can actually get all parts of the Psionics Expanded (work in progress) on Paizo.
Cheers!
Thirding the Aegis class from Dreamscarred's Psionics Expanded: Unlimited Possibilities. Don't be scared off by it being a "psionic" class, as you can easily re-flavor it as non-psionic; it is tightly focused on martial combat and has next-to-nothing mechanically-related to manifesting psionic powers.
You can also combine levels in the Soulknife from Psionics Unleashed and the Aegis to gain access to the MetaForge PrC (also in PsiEx: UnPos) to advance both base classes' core abilities.
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You can also build a Synthesist (Summoner archetype), but both you and the GM are gonna want to be sure to go over your PC's eidelon "suit" build with a careful eye, because they can be very tricky to build correctly. As a player, be warned the Synthesist/eidelon suit is still stuck with 3/4 BAB, starts with only simple weapon proficiency (may or may not be an issue for you), won't be able to use his summon monster class ability very often, and can't melee as effectively if he's also trying to cast spells (again, may or may not be an issue).
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TL,DR: If you want to do some front-line meleeing and some support/buff casting, then you may prefer the synthesist. If you want a strictly meleeing tank (Iron Man or Samus Aran), then you may prefer the Aegis or Aegis/Soulknife/MetaForge.
If you are going for the full PsiEx series, also take a look at the second volume, Find the Mark, for the Soulbolt (Soulknife archetype) to increase your ranged abilities & damage.
I think that an Alchemist would fit into your concept.
Alchemists are very versatile.
Mechanically, you can use the several bombs at your disposal as "Rays". The extracts can be used to buff your armor. The mutagen can be your "armor overload" mode.
You can take the biggest armor available and start flying around.
i made a core class that was exactly for this, but with a more steampunkish style although you can make it any style you want. it has since been playtested and works quite well. enjoy.
Wait Gestalt nice umm If you have the Tome of secrets i would look at the artificer and warlock then the arcane blast from lock makes a good repulsar beam and most other powers could be handle through the school powers and the weird science.
I'll agree, the Summoner Synthesist archetype has an amazing feel and can be flavored though if you want an actual suit, it would work. Personally, I see Tony as an NPC class (Aristocrat) with feats for building and creating.