How to build a humidity meter.

I need to measure humidity for practicing permaculture. I saw two humidity meters at a local shop. The price range were $20 to $15. I thought I would build it by myself.

To build a humidity meter is relatively easy. You need the humidity table either Celsius or Fahrenheit. South Korea uses Celsius as temperature unit.

Parts requirment:
Thermometer x2
water container x1
A piece of fabric?
Mounting materials
Humidity table

Excerpt from http://www.worsleyschool.net/science/files/weather/hygrometer.html

The principle that makes this hygrometer work is that water will evaporate from the wet shoelace, cooling the thermometer to which it is attached. (Evaporation uses heat). This will make the left ‘wet’ thermometer record a lower temperature than the right ‘dry’ one. If the air is dry, a lot of water will evaporate from the shoelace, making the temperature of that thermometer drop considerably. If the air is very humid, little evaporation will occur, and the temperature drop will be minimal.