In this Instructable, I will show you what you need to assemble a tactical light for your air soft gun, for under $10.
Step 1: What You Need
LED light from Harbor Freight (http://www.harborfreight.com/3-1-2-half-inch-nine-led-flashlights-2-pack-97036.html or http://www.harborfreight.com/35-inch-9-led-mini-flashlight-65020.html) Look for cupons that let you get these for FREE!!!
1 inch Weaver style scope rings. Any 1 inch ring will work, high or low profile. I am using NCStar rings (http://www.airsoftgi.com/product_info.php?products_id=9972)
Automotive cell phone charger or cable with 2 wires in it or two wires in heat shrink.
Thin piece of plastic (credit card)
Heat shrink tubing
Stick on Velcro
Electrical tape or Scotch tape
Wire strippers and cutters
Screw driver and allen keys
Step 2: Light Assembly
Loosen the top of the scope rings and slide the light into them and tighten the rings. If the light is too loose, wrap a little electrical tape around the light and try it again. Do not tighten the ring too tight at the end with the screw on cap or you wont be able to take the cap off to change the batteries. You can stop here and mount it to your gun if you do not want a pressure switch.
Step 3: Pressure Switch
Cut a piece of plastic from a credit card. Make it the size you want the switch to be, but make sure it will fit snug in the heat shrink you have. Mine is 5/8" x 1 1/2". Then cut a 1/4 inch slot in the center of the piece of plastic and set aside.
Take the car charger and cut both of the plugs off. Strip off the outer insulation an inch or so to expose the wires. Strip the wires and set asideTake the foil and cut two pieces of foil the size of the plastic part. Poke a hole big enough to insert a wire from the charger at one end of each piece.
Take a foil piece and the charger cord and insert one wire into the hole you poked into the foil and twist the wire around itself and solder the twist. You cannot solder to foil. Be careful not to tear the foil. Do the same with the other foil part. Polarity does not matter.
Put a foil pad on each side of the plastic part and lightly tape around the foil with tape to hold them in place. Be sure the foil pads are not touching on the sides or in the center hole. You can reinforce where the wires attach with some epoxy or more tape.
Take the assembly and insert it into the heat shrink tubing and shrink it around the switch. Mine is tight at the ends but still a little big in the middle.
Stick some Velcro on the switch and then to the area where you will mount it to the gun. I like the plastic hook side on the switch and the soft fuzzy side on the gun.
Step 4: Hooking Up the Switch to the Light
Take the end cap off the light. With a screw driver, remove the rubber button cover from the cap to expose the push button. The cover just pulls out. Then remove the push button by prying it out of the end cap. Take the rubber cover and pierce a small hole to slip the wires from the pressure switch cord into.
On the bottom of the button is a contact. Lift the contact up some to slide a wire under and around it and twist the wire around itself to hold it in place. On the side of the button is another contact. Do the same to this one but make sure this contact is lifted out so it will make contact with the end cap when reassembled. The polarity of the wires does not matter. You can solder the wires if you like. Take care to not melt the plastic.
Look inside the end cap to find a section of exposed metal on the side. The side contact on the button rests against this. Slide in the button with the side contact going in first and press firmly into place. Slide the rubber cover back into place and screw the cap back on the light and test the light. Mount to your gun and your ready for a night game!
Step 5: Use and Problem Fixes
The light can be used as a permanently on light with the push button that is on the light, or, on/off and strobe with the pressure switch. If the button is on the pressure switch will not do anything.
If the light does not work when either button is used take a look if you put the push button back in the right way and also that the side contact is pulled out to touch the side of the end cap.
If the light stays on even when you toggle the button and no pressure on the switch, you have a problem with the pressure switch making permanent contact. Open it up and try to tighten up the pads and make sure they do not touch each other until pressed. Cutting the slot in the plastic spacer too wide will cause the pads to touch.
If you press the pressure switch and the light does not turn on, something must have gotten pulled loose from a contact. Disassemble the end cap and re attach or tighten the wires. If it still goes on, take apart the switch and look for loose connections.
If you toggle the push button and the light does not work or the light is dim, try lightly moving the button inside the end cap around, it was probably damaged when you removed it.