This is a Fos Scale Models "Kit of the Month." I built it "by the book," with only two changes: I substituted a 48-star flag for the 50-star flag that came with the kit, since my model RR is set in 1943. And I used printed shingles from Clever Models instead of the tar paper provided in the kit. The mailboxes and stovepipe are 3D-printed resin and are included in the kit. Since it's 1943, the townsfolk got together and repainted their post office in patriotic colors.
Fos's Kit-of-the-Month models are great little kits. This was a three-evening project that produced a nice foreground kit with a footprint of about 4 x 2½ inches.
The Fos Blog is one of my favorite resources for free scale modeling ideas & techniques. Check it out.