Homebrew PCBs

I recall seeing an article about printing directly onto thin copper
sheets using ordinary laser printers.  This was in some popular
(British? or American) electronics hobby magazine around 1994.  There is
some sort of copper sheet with plastic backing that could be obtained
for $100 (maybe much less, my memory is fuzzy) for 10 sheets or so.  The
sheets could be printed, etched, drilled and used.

The article mentioned printing your pattern on a regular sheet of paper,
then cutting out a piece of the copper sheet, taping it over the printed
pattern on the paper (copper side facing out :-), and running it through
the printer again so that the pattern is printed onto the copper sheet.

I remember thinking, "I won't do that with MY laser printer!"  But it
occurs to me now, that if all four edges of the copper are flat and
covered with tape, it should be reasonably safe for the printer.

There is a kind of cellophane tape used by people who work with
photographic film (for example printing shops).  The tape is thinner
than most tape, adheres strongly, and tends to not leave adhesive behind
when removed.  That might be a good tape to use for taping copper sheets
to paper for laser printing.

There has been discussion in other threads about whether printing
directly to copper in a laser printer can work, given that copper is
conductive.  I don't know why it apparently works, but maybe it has to
do with the paper or plastic insulating backing.

Cheers,
- Jan