1. What you will need:
1x Blaster Water Pistol
1x 3.5 millimeter mono 'headphone' socket
Shrink Wrap (optional)
Soldering iron (15 to 30 Watt power); thin solder; soldering flux; de soldering braid; thin wire (e.g. 16 strand 0.2 millimeter).
Cordless drill with drill bits (1x ¼ inch for socket); Knife or wire strippers; small screwdriver set.
2. Remove Casing
Remove all screws from the gun, then carefully prize both sides apart, being careful not to overstretch any wires.
Lean the controller against something to stop any stretched wires breaking off.
3. Drill Socket Hole
Make a small pilot hole then drill your ¼ inch hole as pictured.
4. Wire up your Switch Socket
Not all sockets are connected alike, so you will need to find which 2 of the 3 contacts you need to solder to.
Attach a test lamp or multi-meter to any 2 contacts. Plug in your switch, then press it. If the lamp comes on when pressed you have the right connections, otherwise try a different combination. There's only 3 possibilities.
Solder two lengths of wire to each socket. Melt shrink wrap around the solder points to help prevent short circuits.
5. Solder to Switch Contacts
Carefully solder both trailing wires from the socket to the two encircled contact points of the trigger switch.
Ensure that the wires will not catch on anything, using cable-tidies if necessary. Grease any points that look as though they may cause friction over time.
If there are any problems, very carefully inspect the quality of your soldering, and look out for short circuits.
6. Fix Socket in Place
After a premliminary test, glue your socket into place then screw it into place tight.
Carefully reassemble the gun, ensuring that no wires catch between the two sides of the case.
The image left shows where to fit Large screws and Short screws.