A simple, easy-to-assemble 3D-printed anemometer. All you need is a 12mm steel ball (a plastic ball may work, but it hasn’t been tested) and an 8cm piece of filament.

Assembly Instructions:

Step 1:
Insert the arms into the hub, then cut small pieces of filament and push them into the holes to lock the arms in place.

Step 2:
Secure the mount where you want to place the anemometer.

Step 3:
Place the ball into the hub, then fit the hub (with the ball inside) onto the mount.

Step 4:
Insert a piece of filament through the hub to lock it onto the mount.

Tip:
If the locking filament piece keeps slipping out, make it slightly longer and bend the ends to hold it in place. Like this: