This Ible will show you how to go from start to finish. I am not a pro at this so if you have some ideas to simplify a step or two please post it. I did a lot of searching to find out how to make everything work.
There were two main sources I used for my ideas and ways to work things out. Here are the links.
diviantART member - fo-ur article
Disclaimer: I am not promoting these sites in any way, I am merely giving credit where credit is due. This Ible wasn't all my doing just something I couldn't find here so I created one.
Step 1: Materials
I used Adobe Photoshop. This just makes the icons look a little nicer and gives you a little more control over the end look. You could also use a free program such as Gimp. I personally have never used it but I hear a lot about it.
Mac with Developer tools, specifically Icon Composer:
HERE is the link to the developer tools if you don't already have it. You may have to create a free account like I did, but it's free and it takes about two minutes.
To check for it, click on:
HD > Developer > Applications > Utilities > Icon Composer
As many or as few as you like. Almost anything can be used to create an icon. Remember larger (in pixels) is better.