This fan fits the Noctua A12x25 metal hub.

The Redux has an updated hub and wingtip, but retains the original blade profile.

This fan, https://www.printables.com/model/299994-xj99c-noctua-nf-a12x25-mod is probably a better design, building off the things I have learned alon the way.

Print 0.1-0.2mm, use support, do some sanding, if you like.

Step file included so you can fit it to whatever hub you want.

Quick testing showed 1-2% improved flow from hub & tip optimization.