Cut the 4 feet of 18g wire in half. I made some measurements when shaping the frame of the bangle, and I use metric, so grab a ruler with centimeters and follow along to my photo and measurements.
Take the 2 ft wires and bend one at 25cm, 3.4cm from the first bend, make a second bend. Take the other 2 ft wire and bend one at 30cm and then 3cm from that bend, make a second bend, as shown.