Put some elastic in the hems of a pair of trousers and create an entirely new look. Making knickerbockers out of trousers is an ideal way to add extra life to trousers that are a bit too short. This is a particularly good idea for kids' clothes, which are often outgrown before they show much wear. If you can sew a straight seam with a sewing machine, you'll have no trouble with this simple fashion project.
Measure and cut
Try on the trousers to determine the length of the knickerbockers. You'll want them to fall several inches below the knee. Place a pin in the fabric to mark the desired length.
Measure from the bottom of the trousers to the pin. You may need to move the pin slightly higher or lower to get a convenient measurement to work with. Measure down 3.7 cm (1 1/2 inches) from the pin, toward the hem of the trousers. Place a straight pin to mark the placement of your cutting line.
Measure from the bottom of the trousers to the lower pin. That is the measurement you'll use to place pins on the cutting line. Place pins about 5 cm (2 inches) apart all around each trouser leg. Cut the fabric just below the pins.
Turn the trousers right side out. Fold the fabric up 6 mm (1/4 inch) all around on each leg. Press. Stitch the legs, using the sewing machine, all the way around, as close to the fold as possible.
Fold up 2.1 cm (7/8 inch) from the stitching line on one leg. Begin sewing near the inside leg seam and sew all around the leg, stopping about 2.5 cm (1 inch) from the beginning of your stitching. Take a couple of back stitches to secure the stitching. Repeat this step on the second leg.
Cut two pieces of elastic, each to a comfortable measurement for the person's leg plus 1.2 cm (1/2 inch). Secure the safety pin to one end of the elastic and thread the elastic through the casing, taking care not to pull the elastic through. You may want to anchor the opposite end of elastic with a pin.
When the elastic is pulled through, return to your sewing machine and stitch the ends of the elastic together, forming a circle. Sew the 2.5 cm (1 inch) opening closed. You can sew the opening by hand if you like.
Turn the trousers right side out, and they're ready to wear.
The thicker the fabric, the more difficult it will be to create a smooth gathered effect with the elastic. Cotton and lightweight wool both work well. If you want to make knickers out of blue jeans, you will need a heavy-duty needle, such as a 90/14, and heavyweight thread.