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Noctua is awesome in a lot of ways, one of them is offering full CAD models: https://www.noctua.at/en/3d-cad-models
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One of the first things mentioned on that page is:

> To protect our intellectual property, certain features – such as fan impeller geometries – have been slightly modified while remaining visually very close to the actual product.

So you do have to 3d scan them yourself if you're trying to print a copy.

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Depending on what printers you have available I'll put in the work to get you a ~0.02mm deviation scan of a blade off a 120mm noctua fan I broke. I expect it to under-perform notably due to the surface texture and the lack of rigidity under load causing contact with the shroud walls at high RPMs, but I wouldn't bet my lunch on it, would be fun to find out.
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The texture has substantial chance to actually help. Check golf balls.
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The materials that you could use in a 3d printer are not rigid enough.

The blades of the fans are fiber-reinforced, in order to have sufficient rigidity, even when very thin.

Only a 3D printer for metals could print something rigid enough, but such a metallic fan would be too heavy for a computer fan.

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Obviously better if you print slow enough. But the fans will be weaker and you won’t be able to pump out thousands every day.
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