Kitbashing Building Flats

I was a big fan of Kingmill Flats before it left the business (I've seen references that he sold the masters to Scenic Express, but they've never come back). I've glued some straight to the layout backdrop, but I fairly quickly realized you can turn them into stand-alone low-relief modules that can be reused and rearranged. For instance, here's a Kingmill flat that I converted to a module with foamcore backing:

Following George Sellios's inspiration, I add roofing and things like vents from Bar Mills, Rusty Rail, etc. One thng I discovered was that in any case, if you just mount the paper flat on a sheet of foamcore alone, the combination will warp. So the extension to the rear adds bracing and strength that keeps the image on the front from warping.

After Kingmill left the business, I found that flats from a vendor called Trackside Flats or an eBay store called Anglie's Trackside Flats are a very similar product. Unlike thre Kingmill flats, they come already mounted on a sheet of foamcore:

This is a good start, but again, just the paper mounted on foamcore will warp over the coming months. So I add a structure behind it made of foamcore. The structure includes an interior horizontal brace that adds rigidity to the front.

I glue the final assembly together with Elmer's glue and hold it in place with a rubber band. Wax paper protects the surface from any runs of glue.

I add roofing to the finished product with textures I find on the web, download, and print:

I've had my Kingmill based modules for five years and more, and none has warped.

I make all my low-relieff flats to a standard depth of 2-3/4 inches. They'll stand up straight, and they can be lined up in any order:

In fact, with this technique, you can build low-relief flats using textures from the web or photos from ghost sign sites. The Joe's Pizza was a flat I found in a Facebook post.

I found the picture below of the Fillmore area on the F&SM on Facebook.

If you look at the background, you can see that Sellios lines up layers of low-relief buildings to give a 3-D impression on his backdrop. Some of those in the photo may be similar paper building flats, but some are commercial plastc models, and others are ones he built himself.

I'm aiming to get a similar scene on my layout using paper low-relief models, including those I've shown here.