I made a diagram to show how Flatlanders use grafting for surgery.
If you ignore the part where they're definitely getting the grafting material from unwilling donors Under The Current Regime™, it's not as horrible as it sounds as a technique. Especially once they get a non-fashist government.
I imagine they're kinda like plants, where their exoskeletons will just latch onto anything even remotely similar, so they've got a 99% success rate with grafting exoskeletons.
And how I imagine them at least, their blood is thick like jelly, not like human blood where it's thin, so their blood helps to hold all of the important internal things in place. It does a lot of the work maintaining their shape to begin with.
[ID: Six simple diagrams of an isosceles triangle with a grey out layer and a purple inner layer, first saying, I'm almost an Equilateral! I have zero fucking rights!!!" with extra exclamation marks. In the second, the triangle is laughing, "hehehe", with a swirl near their head, labeled, "Has been given laughing gas or some other kind of anesthetic". There is now a green smudge on their base, marked, "disinfectant + numbing stuff". The third diagram shows the triangle "fully unconscious now", with floating Zs to show snoring. A small red line marks the base where the green smudge was, with a scribble hand with a knife labled, "pretend this looks like a scalpel", and the further label, "exoskeleton is carefully cut". The next diagram says, "sides are carefully pulled to the sides", with arrows showing the movement of the sides outward a bit. Above this is the note, "The blood is thick like jelly, and helps hold everything in place!". At the base where the side has been pulled apart to create a gap, a darker grey square of exoskeleton is below the gap with an arrow pointing up, labled, "the grafting material is inserted into the new gap". The next shows the triangle's two sides now inside a black Y shaped device labled, "medical clamp", with the information, "sides are compressed and clamped into place", with two arrows pointing inward followed by three lines to indicate continuous pressure, like putting a stack of books on a paper. Another green smudge has been placed on the base over where the new exoskeleton has been placed, labled, "scarring hormone applied". The last diagram is labled, "A Little While Later…" in the font from the transition cards from Spongebob, with the triangle saying, "Yay!! I'm 60 degrees!! I have basic human rights now!!!". Their base is now whole, with only a slightly darker section marked, "Fully healed scar" to show that the surgery happened. End ID.]
If you didn't know, cloning plants, and grafting different plants together, is super easy as long as they're related species, because their bark just goes, "Oh!!! You're part of me!!! Get over here have some nutrients!!!" and heals the cuts until it's all one thing.