Decals can be made with a color laser printer and metallic foils, using
the transfer processes that are used to make one-off printed circuit
boards.

See
http://www.pulsarprofx.com/DecalPRO/Vertical/3_LIBRARY/3d_Other_Decal_Types/Types_of_Decals.html 

Scroll down to the part on water slide decals.

I have had fairly good results using these methods to transfer watch
dial markings and some Doctor Who logos.  The tricky part is using the
laminator to transfer the toners onto the clear mylar film without
wrinkles.  It takes some practice.  I tested these papers while at
Apple on the color laser printer.  This process does not work with
water soluble inks.

The metal foils do work best using a laminator to transfer.  The
binding agent is the plastic pellets in the laser toner.  These are
heat activated.  One does not need a color printer; a black and white
one would do.  The above company sells a sample kit with a wide range
of foil colors.

Do not be confused by the terms "toner transfer paper" and "iron on
applications."  These are all based on paper with a water soluble glue.
One could probably make his own "transfer paper" using hide glue,
paint, and waterproof lacquer.  Glossy magazine paper with a high-
calender clay finish works best.  I do like the original word for this
process: Decalcomania.

The old way would probably be to paint the color layers onto the water-
based glue paper.  Metalized waterproof inks and possibly gold and
silvered leaf could also be applied.   The whole thing then gets
covered with enough waterproof lacquer to bind the pigments together.
When the paper is wetted, the lacquer holds the image together, while
the paper separates from the glue, which remains active.

I got good results on the watch dials using Deft spray lacquer and a
600 dpi color printer.  It looks as good as dials I sent out for
restoration.  There is no heat involved in this method.

Production decals, like printed circuit boards, are done with a stencil
and silk screen process.

Julie Porter