For stickers, I think some people print them themselves on laser printers or use vinyl plotters like Cricut, but the internet has a lot of things for sale. Try an ebay search for "scale construction decals". Some will be normal stickers, some might be water slide transfer decals.
I couldn't find what I needed, so I had a sticker printing service print custom stickers. I wrote a mini-review in this post (good quality, but less flexible than typical RC decals):
https://rctruckandconstruction.com/s...&postcount=100