I use clear decal paper for laser printers, and Microscale Liquid decal film.
Just work up your graphics on the computer, then print to photographic paper.
Take the print out down to the local copiers and run the decal paper through the
bypass tray. Coat the graphic with the liquid decal film, let dry, trim and apply.
I buy the decal paper from a specialty supplier, but Micromark carries a couple kits..
Just search
decal, you should come up with a few options.
http://www.micromark.com/Micromark also offers decal paper for inkjet printers, and a clear laquer spray fixitive to prevent
them from running when dunked in water... Not sure who might be your regional supplier.
Here is a decal, on a 60mm square helipad, from a laser printer,
You can just make out the right edge of the ring... The "H" was applied separately.
You can make out a large red decal on the side of the building and on the crane in
the distance, and a blurred white marking on the crane boom, but I can't reveal
those till the model is presented next Saturday.
The 1mm high white draught markings were done on a specialized ALPS printer.