Elaine, 3M makes a transparency film called PPM 2200 that you can run
through a laser printer or a photocopy machine. Using an iron, you
can then transfer the toner off of the transparency and onto your
metal to act as a resist for etching. The 3M product is not a
resist, just a vehicle for getting the resist from your
printer/copier onto the metal. You can purchase a box of 100 sheets
for about US$21 from office supply stores.
I like this film because it really releases the toner very
completely and takes the heat of the iron well.
[who is even now working on the etching patterns for her SNAG pin swap
goodies using 3M PPM 2200…]