The wind speed meter runs with the wind, faster when the wind blows harder. By counting the number of turns you can tell how the wind speed changes. It does not matter where the wind blows from, because the rotor is horizontal and the cups will cause it to turn when the wind blows from any direction.
You need three plastic medicine cups, tongue depressors from the pharmacy or craft store, they sell colored ones. You need a base, just any piece of plywood or plank, a nail, washer, a piece of square or round wood for the upright and some glue-gun to glue the cups to the tongue depressors. You may also use small screws to attach the cups. In that case you need to drill a small hole through the depressor, tape it first like in the photo.
The disk at the centre is a piece of large diameter dowel wood, I used an old sun-umbrella stick but any round or even square block will do, as long as you can make three saw cuts with a fine saw and push the depressors sticks into the center piece. Use a little glue. The put the rotor on top of the upright with a steel washer in-between or make a small washer from a drinking straw, cut off about 3-5 millimeter and you have a good low friction washer!
Decorate the base and you are ready to show it and try it out…
Oops, make sure you mount the cups all in the direction as shown on the photo; I have made this mistake. If you do it wrong, well, change it!