Here's what I sent someone else on the list who asked for more info:
It's something I used to do myself, and it was useful when I needed
to make a comp on some kind of paper (like cardboard) that wouldn't
fit through the printer. Also very helpful for making birthday cards
and such. We'd just print a mirror image of the design using the
laser printer. Then you turn it upside down on top of the paper you
want to use and either tape it down or hold it very still while
carefully soaking the back of the original paper with the marker,
applying gentle pressure so they toner will stick to the paper below.
You don't want to rub too vigorously or you'll blur the image. You
can carefully peek at the paper below to see how it's working.
I've mostly used this for type, but I imagine it could be used for
high-contrast images. Or you could use a large screen size (maybe
screen print or larger) to get big "dots" to transfer. It just seems
to me that there's no reason the toner wouldn't also transfer onto
PMC. I'm curious to try it myself, now.
Here's a link to a picture of the marker. The picture is of a black
marker, but the number at the top of the page refers to the colorless
blender. I believe they can also be found with a fine tip, but that
maybe a trick of memory.
Good luck! I hope the marker formula hasn't been radically changed
because of cancer-causing chemicals, rendering this information
Courtney Graham Hipp
cgHipp Jewelry Designs