Create a square by attaching four 1-foot segments of PVC pipe with three-way corner connectors. Place a 3-foot section of pipe in the top openings of the two rear corner connectors.
Place a 2.5-foot section of pipe in the top openings of the front two connectors. Place a T connector on top of each of these sections, with the middle openings of the T connectors facing each other. Place a 6-inch section of pipe in the top opening of the T connector.
Place a three-way corner connector on top of each of the pipe segments. The middle of the corner connector should face downward, and the remaining openings should mimic the square below. Attach these connectors with a 1-foot section of pipe between each.
Tie a 1-foot string around the base of each top corner connector. Tie a snap clamp around the opposite end of the string. These clamps can be used to hold the garbage bag in place.
Create the trash bag dispenser by cutting a long slit in the side of a 1-foot segment of pipe. Stuff a roll of trash bags in the end of the pipe segment. Pull the end of one until it protrudes slightly from the cut. Fit this segment between the T connectors above the 2.5-foot pipe section. When one garbage bag is removed, the end of the next will protrude. Remove the segment to refill the dispenser.