I've been giving thought lately to doing this. I'd like to get it done after the track is laid, but before ballasting. A paint pen seems to be the easiest way. I don't like the thought of using a spray can as it would get all over everywhere, and I have an enclosed room where the windows can't be opened.
Woodland Scenics has one, but it seems kind of pricey.
https://woodlandscenics.woodlandscenics.com/show/Item/TT4581/page/1
Has anyone used one of these? How much coverage did you get from each pen?
Testors makes something similar, but it's part of a 3-pack, and with Horizon recently buying most of Hobbico, but not the Testors brand, Testors is in a bit of a flux right now.
https://www.hobbylinc.com/testors-c...rail-tie-brown,-rust-hobby-paint-marker-73801
I do like the idea of Testors Make Your Own Marker.
https://www.hobbylobby.com/Crafts-H.../Make-Your-Own-Enamel-Paint-Marker/p/80792505
The tought of using a brush and bottle of paint doesn't really appeal to me.