Functional elastic, which can be used in concealed waistbands (that is, the elastic is unseen, as it is sandwiched in the fabric

To elasticate a waist, simply take the correct amount of elastic and join the two ends by overlapping a little and zig-zagging together. Devide the band into quarters, marking with pins. Divide your garment into 4 also (usually front, back and sides)

Match the pins of the elastic to the pins on the waist, putting the elastic on the inside (wrong side) of the garment and pin the two together.

overlock the elastic to the edge of the garment. Keep the pins out of the way! Ideally move them down so they do not catch on the overlock knife or needles, but still secure the elastic.

Turn the waistband over again, and reposition the pins to secure the waistband. then stitch in place from the right side using a twin needle.

 Tip, put extra pins in to secure the waistband if its larger, or you are new to waistbands.