Is all wig wag made from vac stack tubing? Are there other ways to prep for wig wag?

Yes.  Wig wags are made from line tubing which can be made a few ways.

Vac Stack

When the crew pulls big glass at the studio they use this method.  When they pull it this way they use an 80mm x 9mm outer tubing with 26 lines of color around a 45mm x 5mm tubing.  This allows the glass to be pulled thinner making the colored tube more stable.  You must know how to do a good termination in order for this method to make a dope wig wag.

Stick Stack

This is when rods of color are usually wrapped around a graphite rod and then inserted into a tube of clear.  This will allow the color to be a bit more dense, as well as it makes it easier for a blower to do a termination.

Linework

This technique gets the same result as the Stick Stack but can be done on a smaller scale.  Many lines can be done inside the tube-like this as it is drawn in like inside out glass.