Source of Small Plastic Letters - Model Railroader Magazine

I used a couple sets from Plastruct to letter my "Post Office Annex" and, fortunately, they were a perfect typeface for those used by the Post Office.

IMG_9388 by Edmund, on Flickr

I printed a sample of the lettering so that I couuld get the alignment and kerning that I wanted and used it as a guide.

IMG_9384 by Edmund, on Flickr

Parcel Post Annex by Edmund, on Flickr

I'll look to see if I can remember where I got the letters. I recall they offer two maybe three? sizes.

 There are other outlets, I posted the above link as an example.

Good Luck, Ed