You will want to do this with the sandal on your own foot. Hair clips work well in keeping the sections to tie off secure until you can finish the sandal.
Sew the short ends of the tie tog. Sew the free end of the connector strap over the sewn ends of the tie.
Rep for other sandal.
FINISHING: If you are making sandals without the flip-flop bottom, turn sandals upside-down and squiggle lines or dots of fabric paint over entire bottom. Let dry before wearing. The fabric paint allows for grip when walking across uncarpeted floors.
If you are adding the flip-flop bottom: Cut the sides and toe divider from your flip-flops. Using the Liquid Nails glue, glue the stoppers or round pegs that hold the sides and toe divider to the bottom of the flip-flop. Let dry. On the sole or right side of the flip-flop sole, draw a line of glue around entire outer edge. Place wrong side of sandal onto flip-flop sole matching edges. Pull apart, wait 5 minutes, then replace. Let dry before wearing.