Take a look at this:
...and now, take a look at THIS:
My intent was to use a bump map to give the impression of a six-barreled machine gun on a simple cylinder. Things took a bit of a different turn.
The material looks pretty amazing, especially if you zoom in and rotate around the gun. It looks like it's made out of semi-transparent crystal or glass.
It's a pretty simple effect to achieve - I used a phong material, with a color and bump map.
Use a couple of gradients on the bump map to turn the single cylinder into a multi-barrel gun.
For the color map...
...create an appropriately angled brush with low roundness and a moderately high spacing attribute, then paint vertically or horizontally along the barrel as appropriate. Use both light colors and dark colors.
Next time: CHAINSAWS!