From my sketches I have generate some ideas and here are some of my development process.
From the start the brief was told to make the icon as 25 pixels by 25 pixels in illustrator so as you see I have used the rounded rectangle and started to develop each application.
For the Altimeter I cameup with the idea of not doing a detail airplane so to make a airplane I used shapes and then cropping the areas that was not needed and then using colours to make it clear.
As you see I used different techniques using stroke for the circle to make it as “meter” around the airplane.
Then for the Anemometer I used shapes aswell and produced several lines to and then used the stroke tool to give as a “wind effect”.
For the Barometer I have illustrate the sun with the circle and another circle with the stroke tool, for the cloudy I have used the pen brush to create a cloud as the storm icon, the rain and the wind.
The decibel meter I used the pen brush to make the “music symbol” and then after I only used lines along with the minus and plus on the side.
Pedometer it was a bit tuff to create it because I have sketch it on my quick sketches and then I tried to illustrate it but it did not come right so what I did was to use the pen brush again and then to get an accurate “step” I decided to use the direct selection so I can manipulate the design and give a right detail.
The speedometer wanted to give the detail of a quick speed image so I came with the idea of using the start of small lines to a bigger line that I also indicate with black colour to show that is actual speed.
For the last one I used the round rectangle tool