Things You'll Need
Instructions
Assembling the Board
Arrange the 48-inch and 21-inch segments into a rectangle, with the 21-inch segments in-between the 48-inch ones.
Drill two pilot holes per corner, centered in the middle of the end of the 21-inch piece.
Attach the frame segments with 3-inch deck screws through the pilot holes.
Place the sheet of plywood over the box frame and adjust so that the entire frame is covered.
Drill holes through the plywood into the frame at every 6 inches.
Remove the plywood, while keeping note of the orientation.
Place a bead of wood glue around the top of the frame.
Replace the plywood, using the pilot holes as guidance for proper placement.
Attach the board using 3-inch deck screws. Make sure each screw is flush with the board to prevent the bags from being snagged.
Cutting the Hole
Make a mark on the plywood board 9 inches from the top and centered in the middle of the board. This will be the center of the hole.
Drill onto the mark with a 6-inch hole saw bit.
Sand the edges of the hole to prevent bags from being snagged as they fall into the hole.