I have attempted to paint the walkway edging on my Rivarossi Cab Forwards several times and give up because my hands are not steady enough to to do that type of detail painting.
What I needed was a miniature paint roller. I searched the Internet without any luck looking for one. Then I had an idea, the 1/2" diameter Dremel cotton buffer/polisher wheels. I slipped the 1/8" Dremel shaft in a 1/8" ID brass tube and I had a miniature paint roller.
Magnified view of my paint roller, the steel shaft is 1/8" in diameter. You can see how the 1/2" polishing wheel looks like a paint roller. I did 14 locomotives with the roller.
The only thing I had to be careful with was keeping the 1/8" Dremel shaft in the brass tubing when I rolled on the paint.
I had to do a bit of touch-up afterwords but very little. I did 11 Cab Forwards and 3 AC-9s in less than 45 minutes.