Clever Models has many useful products in S scale. They make a lot of basic textures that can be used for
sidings or roofs. They also make several S scale kits. They are downloadable PDF's that can be printed out
and glued to various backings to make good looking structures. Below is illustrated some of the ways that I
put their products to use on the Penn Western. Their O Scale structures can be used by reducing the PDF's
to 75% and then using a screen grabber to capture the reduced pages. Their S scale products are under
$10.00 which makes them extremely cost effective.
Here's the S19 Warehouse that was constructed by gluing the paper parts to heavy card stock. Clever Models gives
you duplicates of sections like pilasters, windows, doors, etc. so that when glued on top of the original it takes on more
of a 3-D look.

To the right front is the S09 Steel Shed. I've since moved it to another location on the layout as illustrated below:
The S07 Furniture Factory is a model of an older aged structure. I placed  the factory across from the Saltillo Depot on
the EBT. I used the roof that came with the download for another structure shown below. You can reuse lots of the
parts like doors, roofs, etc. on other scratchbuilt structures.
Here was used the roof from the S07 Furniture Factory
along with separately purchased S Scale factory
windows from Clever Models.
Clever Models has some free downloads
available from time to time. This was an O
Scale Yard Shed that I converted to S by
downsizing the PDF to 75% and then using
my screen grabber (a must have utility app).
Some further notes:

I like to glue the printouts to foam board to make the structures more sturdy.

I was printing the PDF's on to paper, but had problems with the glue bubbling up when I glued the paper to the foam
board. I've lately been printing the PDF's on card stock and had much better results.
The P/N T59 Terre Cotta Building Facade windows were used for this skyscraper.