Description of what is happening inside. I\'m sorry to use what happened on the side of the transmitter as an excuse. The pictures are arranged in order. Color CodeRed = grenade, 40mm type orange = Nerf Mini VortexGreen = Green GasBlue = ValveBlack \"T\" = pin. Picture 1 = transmitter reading 2 = pin pressure valve 3 = valve open, gas explosion. Picture 4-5 = etc. . . . Material: 2 \"schedule 40 PVC or ABS tubes for 2ft or more. Fernco Proflex 2 \"CI, PL or ST to 1- 1/2 \"copper or 1- 1/4 \"PL shield coupler. Part 3001-215. Part 3001-215. Part 3001-215. Part 3001-215. ( If you still buy it wrong, I swear, I will definitely catch you and beat you up! ) Fiberglass cloth 10 \"- 12 \"2 yards wide. Epoxy 1/8 \"x 1/2\" x 24 \"aluminum bar. 1/2 \"x 3/4\" x 1/16 \"thick aluminum angle-\"L\". 1 \"x 1\" square wooden pile. Acetonesheet felt tape back glue. Wax paper roll 24 \"longitudinal mylar head screws and bolts. Crazy Bull XM-spray PB4 40mm grenades ($80)OR1 S-Thunder Multi- Grenades ($65)OR1 S- Thunder foam ball grenade ($60) Tool: Dremel rotate tool-- Accessories: grinding roller and cut-off wheel. Drill and various bit screws tapscrewdriver provides a lot of latex gloves dust maskplastic Cup pictures for epoxy brush and paper: my lightsaber- Not so clumsy and casual. . . An elegant weapon of an era of civilization. Purchase a section of 2 inch schedule 40 ABS or PVC pipe. I use ABS because it is cheaper and it is black. Wrap the tube with wax paper. Then wrap it up with a Mela film. Measure the length of the fiberglass tube and mark it with sharpie. Place the tube on the stand, or run the rod down the middle and pause in some way. You need to be able to rotate the tube when applying resin and glass cloth. Most people use fiberglass matt in small projects because it is very cheap. However, I found it much easier to use a glass cloth because we are using a small diameter curve and the fabric is more flexible. The fabric also provides a smoother finish. Buy cloth 10- 2 yards long, 12 inch wide. 2-cut cloth bag pipe3 layers. I have a choice between polyester and epoxy. I am using general purpose epoxy because it has no smell and does not shrink when cured. Mix the epoxy resin into an external fiberglass tube. For proper mixing, mixing ratio, curing time and treatment, please refer to the resin instructions. This is not a simple explanation. Search for instructures, Youtube, and Google if you don\'t know how to use fiberglass. After curing the glass fiber pipe, pull out the ABS pipe inside ( Wax paper makes it easy) Remove the salad film and wax paper. Throw the Merah and the wax paper away. Buy the Proflex shield coupler. Part 3001-215. It can be found in the plumbing section of any home improvement store. Insert the ABS pipe into the hook and tighten it. The hook is the rear of the transmitter. Insert the pipe/coupler assembly into the fiberglass tube and mark the position where it sticks out the front end. Remove the ABS tube and cut off the ABS tube so that the fiberglass pipe does not stretch out. Remove the ABS/PVC pipe from the glass fiber tube. Decide how much travel you want in-house when you expand your legal transmitter. I decided that my trip was 5 inch kilometers. I marked 5 inch on the side of the fiberglass tube. Make sure that these two points are parallel to the length of the tube. Make sure to remove the abs/PVC tube. Drill the mark out Draw a line between the holes you just drilled in fiberglass and cut out a channel with a dremel tool. Watch out for fiberglass dust. It\'s itchy and you shouldn\'t put it in your eyes or breathe it. Wear long sleeves, goggles and masks. Figure 3: Insert the ABS/PVC pipe into the fiberglass pipe with a coupler attached. Drill holes in the ABS pipe at the front of the passage you just dug out. Figure 4: put a screw in the hole. Now, the pipe will only move the predetermined amount forward and backward ( My trip is 5 inch) The tube inside does not rotate. There are three big reasons why I chose the mad cow XM PB4 40mm grenade shell. 1. There is a filling valve behind it. 2. It has a large gas reservoir. 3. It is loud. 4. There are filling valves behind. 5. Mad cow has a reliable reputation. 6. There is a filling valve behind it. Commonly used for m2o grenade launchers. The filling valve is oriented towards the bottom for easy filling. I use aluminum bars 1/8 thick and 3/4 wide. Iron or steel bars will also work. So is some kind of round rod. Do the best for you. Figure 1: measured from the center of XM PB4 grenade valve ( Silver Circle) To the top of the control box. Transfer the measurement to one end of the trigger bar. Bend the trigger Rod 90 degrees or more. Shape and bend the tip so that the trigger Rod slides forward and will hold down the grenade valve. Figure 2: cut the long end of the trigger rod/Rod to match the length of the control box. According to the material used to trigger the rod/Rod, find a place to fix it on the control box. I used a flat bar so I fixed the bar with \"L\" brackets. Figure 3: attach things (screw, rod, d-ring, etc) Go to the bar so you can grab it and push the bar forward, which will drive down the back of the XM PB4 40mm grenade shell. Make sure that when you expand the launcher, the above (screw, rod, d-ring, etc) Can slide backwards without hindrance. When the transmitter comes down, you want something to stop the above from moving forward as \"safe. Picture 4: * optional * Install the spring to prevent the trigger from accidentally pressing the valve. Pictures 5- 10 is to help visualize the whole mechanism.