Step 1: What You Need
1. Electric fly swat (like the one in the photo)
2. Hot glue gun (adhesive)
3. Nails x 2 (prods)
4. Screwdriver (opening it up)
Step 2: Tear Down
If you suffer from heart problems, be careful not to get shocked.
Take the batteries out of the swat. Use the screwdriver to open it up. Remove the swat part and cut the cables at this end point of the handle. If you are a bit paranoid about getting a shock, touch the circuit board on a cold water tap (ground) to discharge. Remeber it's just a fly swat so it's not going to kill you.
Step 3: Looksie
Have a good look at the open swat and see if you can identify the different components. It's always interesting to see how people have made things.
Touch it! I dare you!
Step 4: Modding
See in the photo how I have circled two cables? This is where the shock is coming from. Peal the insulation back off both cables so that you have a good 1-2cm of bare wire at the ends. This is where the nails come into play - they are going to be the prods that stick out the end of the taser. Wrap the each bare wire around a nail nice and tightly. I used solder to keep them together but the hot glue will be more accessable to most.
Step 5: Calibration
Make sure the nails aren't touching each other while you do this bit. Carefuly hold each nail in place to the side and angle it inwards so that both nails just about meet. See the photo to get a good idea of what I mean. Use the hot glue gun to glue them both in place so that they are quite constricted and make sure the nails are only just out of reach of eachother (about 1mm). I lumped more glue on once the previous amount was dry to keep those nails there!
The reason why I designed the nails to be so close and almost touch is so that when you turn it on, it will do something rather than just do nothing until someone accidentaly falls on the prods. Because the voltage is not phenominal, you can't have too much of a gap between the nails. It still looks and sound good when activating it by itself. I can imaging if you had an attacker, this would make them think twice and you wouldn't even have to hurt anyone!
Step 6: Finish
Once the glue is in there, put the casing back together and add more glue to fill the hole at the front there the swat bit was. Put the batteries back in and have fun. You can see in the photo below, it is back together! Check that still photo of the electricity! Oh... yeah...