When assembling pipes, first clean each surface that will touch another (except the thread end) with PVC cleaner. Then, after a minute, swab glue on the sections, one section at a time and combine. The flush bushing and 1 1/2" piping should be connected to one end of the "T" adaptor's "4 end. Put the and the cleanout plug and adaptor at the other end. Cap the smaller handle end with any PVC cap that fits.

Once all sections are joined, allow the gun to dry for an hour (again, not indoors). While it's drying, attach two wires to your push button grill ignitor with the electrical tape. The ends of the two wires should be bare and make a purple spark when put very close to each other.

Next, screw two screws through the top of your "chamber" (the 4" section) slanting towards each other, until they are little less than a pencil's width away from eachother inside the gun. Attach wire ends to the outside part of the screws with electrical tape. Test the connection: you should get blue sparks off the end of the screws every time. If not, check your connections or change the gapping on the screws. The biggest single problem with potato guns is people don't get a consistent spark .

Once that works, move to an unpopulated area. Bring a tasty beverage (like a Coke). Using a stick or broom, stuff a potato down the 1 1/2 inch "barrell" end of the gun until it is back near the chamber. Unscrew the "4 cap on the back of the gun and spary in accellerant. The best I've found are hairspray or dabs of PVC cleaner. Spray hairspray inside for about 3 seconds or drop 3-4 drips of PVC cleaner into the chamber and quickly and firmly screw the cap back on; point the gun away from anything living.

Push the button on the grill ignitor.