This demonstration by 8mm shares techniques for creating wig wag designs. He shows how to bend small sections of heated tubing, then bend the tubing while turning the piece in the flame. As the piece is turned, the bending causes a bump to appear in the lines of the tube, which allows for more back and forth, or wig and wag, in the design.
To view the whole document, download for $5.95 Bender Back Wagination