You can build a simple dispenser for your trash bags using 1/2-in. pipe and a few fittings. Screw a floor flange to the cabinet, thread in a 3-in.-long pipe nipple, and then thread a 90-degree elbow onto the nipple. Cut the vertical pipe so it’s a bit longer than the width of the roll of bags. Thread the vertical piece into the elbow and slip on the roll.