Use a tape measure to measure a 14-inch diameter circle; cut the circle from the flannel fabric for each table leg bootie desired.
Fold the outer edges of the circle in 1 and 1/4 inches against the wrong side of the fabric and pin the fabric in place. This will be the casing or the "tunnel" for the elastic to thread through.
Using the straight stitch function on the sewing machine, sew around the pinned edges using a 1-inch seam allowance, leaving a 3-inch opening/gap unsewn (where the elastic will enter/exit). Remove the pins.
Cut a 6-inch piece of 1/2-inch wide elastic for each table leg bootie.
Connect a safety pin to the end of a piece of elastic. Connect the other end of the elastic to the fabric at one end of the elastic casing/tunnel. This will prevent you from losing the elastic within the casing.
Feed the safety pin/elastic through one opening of the casing until it emerges at the other opening.
Sew the elastic to the fabric, and sew the casing closed. Usually a simple straight stitch and then reverse straight stitch will secure the elastic and the end of the casing.
Turn the table leg bootie right side out and stretch the elastic opening over the end of each table leg.