As mentioned in prior posts, Tichy decals can be purchased in OO scale versions. One set that caught my eye was this one, for a
Back in 2017 (more here) I first purchased Tichy OO decals, which they will make on special order, scaled up from their HO decals. I
A classic publication that was hugely influential back in the day was The Model Railroader Cyclopedia. The classic version of this was published in one