Step 1: Find a Gun
Find a gun to use as a base for your project. I've heard a lot of loose talk about steam punk guns of late, but for this project I was looking for something a little more like Hellboy's "The Samaritan." That is heavy, high caliber and steel. This gun body was a perfect fit and only $2 at my local urban appropriation center. It started life as a playstation light gun and was full of more electronics then your run of the mill toy pistol.
After removing all the screws holding the case together I examined the contents. Of the original hardware I'm going I kept the trigger assembly and the A/B buttons. Everything else got cut out. Be careful to leave longer wires connected to parts you might use, this will save extra soldering later on.
I like to photograph the insides of things as a i take them apart, so i know where everything goes during the rebuild. There's nothing worse than being done and not remembering where that last bolt goes.