A few points:

1) This is a rocket launcher without a rocket I will leave it up to the end user to design your own munitions.

2) This device will be considered by many law enforcement agency's as a weapon DO NOT AIM AT ANY THING (other than open sky) I AM NOT LIABLE FOR ANY INJURIES CAUSED BY THE USE OR MISUSE OF THIS DEVICE.

3) I know the title says "PVC" but in the photos the plastic I am using is ABS plastic pipe from the Home Depot.

4) This device is designed to ignite Estes model rocket engines.

5) The launcher costs around 40-50 dollars without the cost of the electronics,wire,etc.

6)I apologize for not taking pictures as this is my first instructable and I had already built this before finding this site.

Step 1: Gather All Materials

Materials:
1.)-4" flange
2.)-4"-2" hookup
1.)-2" end cap
1.)-4" coupler
2.)- 2' sections of 4" ABS pipe
1.)- roll of electrical tape
1.)- X-acto knife or wire strippers
1.)- 9v battery
1.)- Radio Shack toggle switch with safety cover
1.)- Drill w/ bits
1.)- 7' Speaker wire, I used model the rocket launcher's igniter wire
1.)- hacksaw
1.)- 9v battery snap

Step 2: Where to Drill

Drill a hole large enough for the toggle switch on the concave side of one of the hookups and on the convex side drill a hole for the wires to pass through (see badly drawn diagram)connect the wires to the relevant areas(I twisted the wires through the holes in the toggle switch to make the connections).

Step 3: Assembly

After wiring up the electronics in the hookup assemble the piping after cutting one of the 2' pipes in half so that the order of the fittings is (from back to front) flange,2' pipe,shoulder rest hookup,1' pipe, electronics hookup w/ 2" cap on bottom, 1' pipe, coupler.

Step 4: Finish

All you have to do is run the wires to the back of the main tube and connect them to the rocket.

You could use ABS cement to fuse the pieces together but i didn't and it works fine.