Align the carpenter’s square with the longest side of the board to determine whether the board is square so that correct straight cuts can be made later.
Run the board through a jointer, a woodworking power tool with a parallel fence and blade used to straighten woodcuts, or file the edge square with a power sander, such as a belt or orbital sander, or a woodworking plane, which is a hand tool that shaves away wood to smooth the surface.
Align the squared edge of the board with the fence of the table saw to keep the cut square, and cut the board to 5 inches wide.
Place the carpenter’s square against the perpendicular side of the board to check if it is square. Repeat step 2 to square the edge.
Set the squared edge of the board against the table saw fence and cut the piece to 25 inches long. The board should be a 5-inch-by-25-inch rectangle.
Sand all edges with a belt or orbital sander, rounding the edges if desired.
Drill a ¼-inch-thick hole at each corner though the board and into the wall where the rack will be installed, such as an area near the kitchen sink or dish rack. Insert the anchor through the holes and into the wall, then twist in the screw.
Install the rod holders with screws 2 inches in from the 5-inch edge of the board. Insert the dowel into the rod holders.