While Iron Man is known for ultra-sophisticated armor that makes him a match for nearly any superhuman, Tony Stark's caveman suit turns him into something closer to the Hulk - a shambling, terrifying behemoth who nonetheless draws on cutting-edge technology... at least for his time.
Marvel's Iron Man by Design initiative challenged artists to design unique suits drawing on specific time periods and artistic styles. In the hands of master creators, Tony Stark became a gladiator, an Atlantean, and even gained some Art Nouveau armor that makes him look like an Eternal. In each case, Tony's advanced technology was given a new spin, however in taking him back to the dawn of humanity, Marvel created a decidedly low-tech version of Iron Man who challenges what 'technology' even means.
Created by Christian Nauck, and published as a variant cover for Deadpool: Merc with a Mouth #10, Tony Stark's caveman armor uses fur, bones and wood to turn him into a Hulk-like powerhouse. Towering over his modern armor, this suit utilizes natural materials to protect the wearer, and sees Iron Man brandishing a flaming brazier. What's fascinating is that for the time period, this suit is every bit as advanced as Tony's modern armor is today. After all, humanity's mastery of science depended on early scientific observation and technical invention. In the modern day, Tony's very first armor is laughable, but one day in the future, his most sophisticated tools and weapons will be likewise outclassed by the march of time. Tony exists on the bleeding edge of technology, but he's ultimately always a caveman, discovering and creating new horizons that his descendants will take for granted.
Of course, even in Marvel's main canon, the Iron Man identity was indeed created in a cave using whatever materials were to hand. The monstrous caveman armor lays bare the fact that Tony wasn't just creating a suit but a weapon - one intended to strike fear into the hearts of his enemies. Marvel has drawn many comparisons between Iron Man and Hulk in the past, with the recent Iron Man #18 (by Christopher Cantwell and Lan Medina) suggesting that while Tony Stark's alter ego may seem less chaotic than Bruce Banner's superstrong form, Tony's inventions have ultimately caused similar levels of harm, both to himself and others. It's interesting to note that in his earliest appearances, Bruce Banner attempted to keep the Hulk trapped in a cave, only for the Green Goliath to emerge at nightfall and approach the world on his own terms.
Speaking in Marvel's Iron Man by Design collection, Nauck says he "wanted to give him a hunched, a raw, cloddish look that reminds you of a caveman, even if you can't see his face... Even in his primitive incarnation he had to look inventive and powerful. His armor is handmade - raw, but well thought out, ahead of his time." Tony Stark's genius is in his unique ability to take the materials around him and build something greater than its parts, but that genius is always interpreted through his experiences as a creator of weapons.
While Tony's inventions haven't individually gone as wrong as Bruce Banner's gamma bomb, they've cost lives and caused disasters, even as Iron Man strives for heroism. There are plenty of differences between Iron Man and Hulk, but in portraying this prototypical suit as at once brutally powerful and darkly inventive, artist Christian Nauck manages to expose the dark ties that bind their stories together.
Source: Iron Man by Design