I didn't want to clog the October 21 workbench with this infomercial but with all the attention to modern graffiti ModelU in the UK has scanned and is 3d printing a series of graffiti spraying artists/hoodlums in case you want to depict them caught on camera in the act.  They will on request print them in 3.5 MM/HO scale and US 1:160 N scale. They are expensive and postage is almost a killer but if you want to depict the act in progress these will do the trick. 

https://www.modelu3d.co.uk/product/1733/

I'm beginning to make some structures for my layout and finding many of my kits have poor model roofs. Feeling that roofs are so visible and thus important, I intend to replace with sealed seam metal roof and asphalt roof sheets from Evergreen, Micromark, respectively.

Question though: How do you experienced modelers solve for the roofcaps necessary on these roofs, how do you fabricate the roofcaps and what strip styrene do you use? (I'm modeling in styrene, not wood).

Because I don't like the shiny look of decals, I am searching for N scale signs that I could color print and add to my buildings.

Do you have files with those signs?

I experimented with my wife's RubnBuff wax to create steel plates.

I just used my fingers to rub in it on the paper also paint to depict rust.

Just test fitting them and will later put some dents in them to show evidence of logs and drift wood colliding with them in the past.