I started with the idea of a dueling set after seeing this video http://www.youtube.com/watch?v=BsE_wBnOZ3s&feature=related
You will need the following.
A small block of wood.
2mm brass tubing
Stain for the handles
Match box and matches
Foam air filter thick enough to use in the case
Cap gun caps(only if you want to shoot it)
Paint Brush or Q-tips
Step 1: Make the Gun Barrel
Cut a piece of 2mm ridged copper tubing the length of what you are looking for in a Barrel for the gun.
File off the cut end of the tube to make it smooth. Then solder one side of the tube closed. Make sure that the end is sealed completely.
Once the solder is cooled, use a wire to see how far the solder has entered the tubing. This allows you to figure out where to cut the slot for the fuse. You want to be as close as possible to the sealed section of the barrel but not where its sealed. Then file a slot into the barrel for a fuse. Don't cut too deep, all you want is room for a fuse to slide in.