Ignoramus12493 writes:

Print a mirror image on a laser printer, transfer toner like a decal
with a bit of acetone or xylene.

Richard, just how is it done? It sounds very interesting.

Not much I can add. Press a mirror-image print against the work, dab
and press with a solvent-moistened paper towel to transfer the
unmirrored image of toner to the work. If you foul it up, erase the
work with solvent, and try again with another print copy. A bit tricky
to get the pressure and amount of solvent just right, but cheap to
practice and learn at it. Some of the parts on one of my Web pages show
examples of this method of marking:

http://www.truetex.com/micad.htm

Such as specifically this image:

http://www.truetex.com/micad21.jpg

This is based on the fact that most laser or copier toner is styrene
binder with carbon black pigment and possibly iron oxide developer. The
solvents are chosen to melt and transfer the toner, but applied
sparingly so as to not make the toner run.

Some metals like aluminum (the normal surface oxide, not elemental) are
hard to transfer to, and may benefit from a thin layer of clear Krylon
or epoxy before attempting toner transfer printing. (I leave it to you
to research how one gets Krylon or epoxy to stick to aluminum.)