A clam gun is not a "gun" at all, but rather a simple device used to dig for clams. The clam digging gun is a tube made out of PVC, or metal, with a hole in it to let air out, a cap on the end and handles. When the digger sees the telltale depression or hole left by a clam beneath the sand, he places the clam gun over it, pushes it down, covers the hole and pulls back up. The clam digging gun will suck up the sand and the clam with it.
Cut a 4-or 5-inch diameter PVC pipe to about 2 feet in length. Make it slightly longer if bending is difficult for you or slightly shorter for children. This will form your digging tube.
Cut a second piece of PVC pipe. Pick a thickness that is comfortable to hold and cut it to about 1 1/2 feet in length. This will form the handle for your clam gun.
Glue an end cap onto one end of the digging tube to form an air tight seal. Let it dry.
Place the second PVC pipe across the top of the end cap. Have a friend hold it in place.
Wrap duct tape around the place where the two pipes join, forming a thick, stable layer of tape. This will form the connection between the handle and the digging tube.
Drill a small hole in the side of the digging tube about 6 inches below the end cap. This is the air hole to create suction when you pull the digging gun out.
File the open end of the digging tube so that it tapers to a sharp edge, using a rasp or rotary tool. This step will allow it to dig more efficiently.