A homemade stun gun is quite an easy hardware hack, all that is required is;
1)A disposible camera (Perferibly a Kodak one)
Step 1: Take Apart Camera
Step 2: Remove Batery & Work
You'll see a little light bulb about 3/4 inch long. Carefully remove that with out destroying anything.
Step 3: Solder Time
Step 4: Press Buton
Step 5: Saftey First
Because this isn't very safe and you have a chance of getting shocked, (personal experience) an easy way to make a protective case is to.
Step1) Cut apart the hard plastic inside of a "Five Star" binder. The tough plastic is very flexible and and can just be glued together.
Step2)Cut to fit the stungun inside.
Step3)Glue together. Don't forget to cut a hole for the button, cardboard works as a good depressor so you don't have to make direct contact with the button. Also slapping a cut up rubber glove over the stungun adds extra protection.