Determine the size of your adjustable gate. Fully extend the curtain or shower rods and measure their length. Decide how high you want the finished gate to be. Most pet or baby gates are 33 to 36 inches tall.
Cut the fabric. Cut a piece of fabric as wide as the fully-extended rods and as long as the desired gate height plus 4 inches. If the fabric is not wide enough to cover the entire rod, cut two lengths of fabric that add up to the rod width plus 1 to 2 inches.
Sew the fabric. If necessary, join two narrow pieces of fabric to make up the full width of the gate. Hem any raw edges by turning them over twice to enclose the edge and stitching them flat. Turn down 2 inches of fabric at each end of the fabric, folding the raw edge under. Stitch carefully along this fold to create a pocket for the curtain rod.
Insert the rods. Remove any decorative ends from the curtain rods and slide them into the rod pockets. Replace the ends and arrange the fabric on the rods so that it lies smoothly and covers the entire rod.
Install the gate. Adjust the rods to the desired width at a slight angle to the doorway you wish to block off. Press the rod down flat to put increased tension on the entire assembly and prevent children or pets from knocking down the gate. When the doorway is smaller than the full width of the fabric, slide the bunched material along the rod so that it gathers evenly for a more attractive appearance.