I am a chemistry buff and also had a look at the original research paper. Aticle is open acess if anyone is interested https://www.nature.com/articles/s41557-025-02055-9. So here is the way too long explanation.

Sadly no, they didn't discover an entirely new class of double bonds that are stable in this bent configuration. Instead those bent double bonds are very reactive and therefore can't exist for very long. But they are reactive in a specific way that proved useful for attaching those big 3D shapes to something else in interesting ways. That means that the double bonds are "used up" in the reaction and are no longer present in the new molecules they made.

The clickbait headline in general just puts way too much emphasis on the unusual double bonds. It is not a new concept in organic chemistry at all that double bonds can be strained (=bent out of plane) and that they become more reactive when they are. The perfectly flat case is just the most stable geometry for double bonds, which makes it more difficult to have molecules that force them to be bent. Because of this the bonds in this case could also be more accurately described as one-and-a-half bonds than "true" double bonds.

Brendt's rule (roughly, that you cannot have molecules where double bonds are strained this much) was not considered an unbreakable "principle that had stood for more than a century" at all. The first counter examples, including the ones in the article, already popped up in the eigthies, around 60 years after he established that rule. The remaining of the article actually represents the research paper pretty accurately, just the headline and first two paragraphs are heavily sensationalized.

TLDR: The molecules in the article are just two pretty extreme cases of bent double bonds that have been known for decades. The researches here "just" (this is still impressive work) managed to use these weird edge cases of double bonds for some interesting new reactions that provide a shortcut to structures that would be a pain to synthesize in another way. Is this actually immediately useful for drug discovery? Maybe. Someone made some interesting new shapes in an easier way for other scientists to play around with. Maybe that helps with something, maybe it does not. But now we have one more tool in the chemistry toolbox to try and make new helpful molecules.

Now that you mention it, just creating an "item" that is effectively just an armor flavored as tattoos has its own advantages.

For example, at higher levels the character could apply armor runes directly to their body. Thats pretty cool in and of itself and also in tune with the idea of expanding the tattoo with different effects. All with minimal effort and without having to worry about balancing issues because the rules are already there.

Just noticed from the other comments that my option a is just the same as an archetype without the archetype part... so yea, still have to get used to how PF handles these things myself 😅

As far as I understand it, archetypes are more of Pf2e's way to do 'multiclassing', where you choose feats from an archetype instead of your normal class feats.

So you're right, there is no direct correspondent to DnDs subclasses in PF2e. But many classes still have subclass-like specializations. They have different names for each class, for example 'ways' for the gunslinger, 'instincts' for the barbarian or 'arcane theses' for the wizard. These in themselves tend to have a little less meat than 5e subclasses, because you still have a lot more customization options with your feats. Mostly they modify a core element of the class and also give acess to specific class feats.

Sadly, the fighter seems to be be the odd one out and is designed to not have any such specializations. Maybe so it can be a beginner friendly class that doesn't overwhelm the player with choices..?

So as I see it you might:

a. just make some appropriate fighter feats for your culture that any fighter can choose (with whatever restrictions you place on that as the GM, regarding backstory, etc.). This would be the easiest in my eyes, as you could orient yourself on existing feats for how much these should be able to do.

b. you could make this an ancestry/heritage thing, seeing that it should be tied to a culture. Maybe not exactly what you want, if it is supposed to be for fighters only. Could work as just a generally available ancestry feat/series of feats that players can choose. However these often don't make mayor changes to a character and rather give a small bonus to something.

c. make a new class that gets all the same stuff as a fighter, except for some things you replace with your own homebrew. This might get a bit more complicated than creating additional feats.

d. figure out how to modify the entire fighter class to offer a subclass-like choice. I wouldn't know where to start on this one. This would easily break something in how the game is balanced and feels like a job for people who are on a level of understanding this game on par with the designers at paizo.

Just as a final note: I haven't really started to homebrew much in PF2e myself, so my ideas on this might not be super accurate.

I think (some of) the hostility towards homebrew might come from the fact that PF2 plays very much "numbers first" in the sense of balancing. So I feel this is one of its greatest appeals for players of the cellar lizard game who couldn't stand the wobble of that system. When those people associate "homebrew" only with "fixing the dang game" of course they get confused when people try to "fix" a game that doesn't have any such glaring mechanical oversights.

That's of course not helpful though. As I see it, mostly people homebrew because they are going for a different experience but with a familiar game system or just 'cause it's fun to try and see what you can do with the game.

I've only been running PF2 for a short while and haven't really tried changing anything as I believe I should know how it works before messing with it. In other systems I've homebrewed quite a lot and optimizing the balancing was more of a helpful creative framework and never the sole point of it.

So yeah, I like the idea of encouraging people to share their rule variants. Wasn't this the whole point of having a better open license anyway? So everyone could share their custom stuff without worry and everyone else would have a better and richer game for it? 😁

(with homebrew here I mean changes to the core rules only and not adding your own creatures/items/... That I already do because it's baked into the core rules in PF2)

The crafting rules. You spend at least 4 days to make an item for the same price you could have bought it for.

Oh, you can spend additional time to get the cost down to half, with the same rules as earn income? Well, you could also earn income the whole time, just buy the item and still have more money left than if you made it yourself.

I get that the rules are that way to prevent players from taking item balancing completely out of the GMs control with huge discounts. But it just feels bad for a player to invest into crafting only to be "allowed" to waste 4 extra days to essentially buy an item.

I personally think so. It is in many ways similar to 5e but a bit denser on rules. It feels like the designers really wanted to make sure that there were no weird corner cases. And while there is a lot of them, the rules all seem very logical and consistent. So when playing it feels a bit more "mechanical" or "game-y" but also less wonky than 5e can be. It is a somwhat different experience than 5e and the rules are available for free at Archive of Nethys. But if you should pick it up really depends on whether your group is unsatisfied with DnD or itching for something new. Our group changed over after trying a one shot and because our DM was getting a bit bored with 5e.

Yeah, just a case of sausage fingers.