(in paint.net)
For the way I do it I take a screen shot of the model first from the side. While it is still big, I delete the parts that arnt of the gun (background whatever) so I just have the gun. I then use fill can. As I only use up to 4 colors max I can use different shades of red easily according to what color the thing is. Ignore shading, just base it off of the original color. For each shade darker, I use a darker red, 20% each time. 100% red (all other colors at 0) for the brightest, usually 20% red for the darkest. I then crop the image to only the gun and resize it so the height is 22. From there I redo the colors. Delete the pixels that are barely shaded with color. And match the pixels between shades to appropriate colors, still using the 5-tone reds from before. After you do this, outline it in black.
Viola, a CI icon that looks just like the original thing.
Later when I finish up my Laser Shotgun I will post a series of pics for making the CI for that if you didn't get this.
