I did not had the intention of measuring wind speed. So its actually more like a toy

i was sad about destroying ping-pong balls so i made shell drawings almost like an eggshell yet bottom part is spherical and that part is 42mm in diameter

Thin shell has a 1mm rim and than shell it self is 0.5mm with 0.4mm nozzle extruding 0.5mm line with 0.15m layer height it is printable with some supports.

at first i have printed one of the bigger Anemometers( https://www.thingiverse.com/thing:4540340) but i needed a smaller one.

after experimenting i decided a light design with light bearing is better

while printing
for spinners they need to be as light as possible 2wall %20gyroid 3top/botton should be ok

for bearing interface (aka axis) i always printed them with lots of walls so they became %100 plastic

For mounting i wanted it to be as clean as possible so MAGNETS were great for me
i used magnets from old HDD lying around thy are usually pretty strong you can fit any magnet up to 2.6mm thickness

you can modify or create any type of mounting interface (please share them with me)
you can use even use "Wall_mount.stl" of thing:4540340

for assembly

for a light flywheel 3 x thin_shell is needed. but Shell.stl is also ok( easier to print)

and you can also use cheapest Ping-pong/Table Tenis ball. you need 3 of them
i used Hot Glue Silicon but its up to you.
i also used hot silicon to seal magnet inside the mount part.

608z (ID:8, OD:22mm, T:7) bearing is very straight forward just put them together.

but for 623ZZ (ID:3, OD:10mm, T:4) you will need M3 8mm (minimum:6mm) screw
any screw is ok jut make sure it fit ID of the bearing :)

here is the cad files if you like to edit them for yourselves:
https://cad.onshape.com/documents/701aee7c9f91d964009aac63/w/dc492b1e65bd901bf24c461a/e/287822b43a9eb6b0d06fb256

Green pinwheel --> https://www.thingiverse.com/thing:4844900