Here is a summary of the solution.

I bought a few road sign blanks for this project where I found that most
are aluminum, painted white, often but not always pre-punched, and anywhere
from 0.100" of an inch thick to 0.060" thick.

I found the 0.100" sign couldn't be easily bent by hand whereas the 0.060"
signs could be bent by hand relatively easily but seemed sturdy enough for
withstanding weather purposes.

This link covers the details of the font legal and compatibility issues:
- https://groups.google.com/d/msg/rec....A/FCyiDz1TAQAJ

Where the summary results are that roadsign fonts are tested under
real-world conditions for specific things such as halation, night-time and
speed legibility (especially when tight interstices are involved),
cutout-integrity, removal of tiny notches in joints of the letterforms,
negative spacing compactness (affecting legibility of signs in
negative-contrast color orientations), common symbols, etc., all resulting
in an increase in accuracy, viewing distance, and reaction time.

The official USA roadsign font is "Highway Gothic"

Another previously-official US roadsign font is "Clearview"
A common USA Gothic-look-alike freely distributable font is "Roadgeek"

In Europe, and specifically in Germany, the road sign font is "DIN 1451"
The Mac ships native with a DIN-1451-look-alike font named "DIN".
The latest Windows ships with a DIN-look-alike font named "Bahnschrift"

Windows MS Office can embed the entire font set which works for Windows.
Mac MS Office can¢t embed fonts & can¢t read embedded fonts.
The Mac has an issue seeing the DIN font (see the Usenet url for details).
Sierra
- https://support.apple.com/HT206872
Maverick:
- https://support.apple.com/HT201375
- http://www.jklstudios.com/misc/osxfonts.html

Highway Gothic fonts are available at cost he
- https://www.myfonts.com/fonts/pixymbols/highway-gothic/
Highway Gothic seems to be available for free he
- http://www.dafont.com/highway-gothic.font
Clearview is only available at cost (AFAIK):
- https://en.wikipedia.org/wiki/Clearview_(typeface)
Roadgeek is available online for free in many places, for example he
- http://www.fontspace.com/michael-d-adams/roadgeek-2005

If you know more about the fonts than the summary above, please respond so
that we can learn from what you've experienced.