UPDATE: Check out the newer version of this file that lets you select from all the Canadian Provinces and Territories (http://www.thingiverse.com/thing:1781423)
Customizable Ontario (Canada) license plate.
This is part of a car costume (http://www.thingiverse.com/thing:1770501) and the default size is 120mm x 50mm.
This file uses the Windows Font "Univers 57 Condensed". I have made this a setting if your PC doesn't have the font or you are using customizer it should switch to a default font.
I used a blue sharpie marker to colour the letters.
I used Inkscape and a plugin called paths2openscad (http://www.thingiverse.com/thing:25036) to convert a blank plate (jpg) to an SCAD file then added the text. It should be easy to duplicate it for another province or state.
UPDATE: I added a variable to squish the text because if the wrong font file is missing it runs off the plate.