For my project (jet-fin for my windsurf board / SUP) I am looking for different impellers.
Maybe this thread would be a good place to collect and share the impeller designs.
I prefer .stp files, because they can be easily adapted to your own requirements.
My own 63mm impeller (stl and stp): https://www.thingiverse.com/thing:4037199
Optimized for 3D-Printing with 0.4mm nozzle. Printed in PLA+.
The blades cannot be broken by hand even with pliers you need a lot of strength to break it.
Tested with SSS56114 / 500KV on 6S.