how do you make a wind sped gage
To buttress what steveastrouk wrote, see: https://www.instructables.com/id/Wind-Speed-Meter/
The simplest way is just to use an arm, pivoted at the top, and with a plate for the wind to act on it, the higher the arm is pushed by the wind, the higher the windspeed.
Alternatively, a "proper" anemometer could be made by attaching cut sections of ping-pong balls to arms, and attaching them to a cheap motor. The voltage generated as the wind turns the arms is, to a first approximation, proportional to wind speed. You could calibrate it with a voltmeter, while it is fixed to the top of a car !