Homebrew PCBs

IMHO, the qualities that make paper useful for TT are either:

1. They have a water-soluble coating on them, or
2. They are glossy so the toner just doesn't stick well

#1 is met by cheap glossy magazines, which use a clay coating to get the
glossy look.  Pulsar TT paper and press-n-peel also have a coating on
them.  Thinner paper lets the water get in faster; thicker paper will
need more soak time.

#2 is how transparencies work.  The plastic is so smooth that there's no
mechanical bond between the toner and the film, so the bond with the
copper is stronger.

In either case, results improve when the copper is properly cleaned and
scuffed (too smooth and the toner won't stick as well!).