Things You'll Need
Fabric, as determined by window size
1/2-inch bias tape, as determined by window size
Tools for hanging curtain rod
Triangle curtains are so easy to make. They provide simplicity to a window and a touch of whimsy. If you have never sewn curtains before but would like something a little different than ordinary straight panels, then this window treatment is the one for you. You will want to choose fabric with a design that can be turned upside down, but doesn't look like it's turned upside down and has no wrong side. Left unlined it provides a fun geometrical shadow all the way to the top of the window, but it could be lined. These instructions are for a basic triangle curtain pattern. They hang flat and have no header which allows them to keep their triangle shape from top to bottom. The curtains do cover most of the window, so keep that in mind when choosing fabric colors.
Hang your curtain rod. Measure the width of your rod, including the return. Add 4 inches to this total. Measure to where you would like the curtains to fall. Add 4 inches to this total.
Cut one piece of fabric using the width measurement and the length measurement. Using the yardstick and the tailor's chalk, draw a line from one top corner, diagonally across the fabric to the opposite bottom corner. Cut the fabric in half on this line.
Turn so that both pieces are at right angles with the width at the top on both pieces and the length on the right side on one piece and the left side on the other piece. Fold to the back and iron a 1/2 inch on one long side of one panel. Fold a 1/2 inch again and pin. Top stitch the hem as close to the folded edge as possible. Repeat for the opposite panel.
Pin the wrong side of the bias tape to the wrong side of a triangle curtain panel, along the diagonal cut. Sew the bias tape to the diagonal edge using a 1/4-inch seam allowance. Fold the bias tape to the front of the panel and pin. Top stitch as close to the pinned edge as possible. Press the bias tape trimmed edge. Repeat for the other triangle panel.
Lay one panel on your work surface with the wrong side up. Lay the other panel piece on your work surface over the first panel with it's wrong side up also. Match the top edges and pin. Stitch a 1/4 inch from the top edge to hold the pieces in place.
Fold the top edge a 1/2 inch to the wrong side of the triangle curtain and press. Fold the top edge over again 1 1/2 inches and pin. Top stitch the pinned edge as close to the edge as possible to complete the triangle curtain rod casing. Thread your rod through the casing and hang.