How do you paint rings on missiles/bombs/tanks?
Definitely not an expert, I suggest a fine brush, I’m using a 20/0 Petite Liner from Michaels. The long thin bristles will tend to stay aligned as you twist the round object under it.
I use decal stripes. Can be tricky to get them straight, setting solutions will help. Works best on missiles with straight bodies.
Have also had success painting bombs yellow first, masking the stripe and finally painting the bomb case colour.
For some of those things, I like using Sharpie Ultra Fine point enamel paint pens. On other ones I’ll use decals or paint brushes. If you look at close up photos of the real things, sometimes the stripes were not painted on too neatly.
Another method - gently fix your bomb/missile in a standard power drill with a low speed screw-driving option, ensuring it’s “true” in the chuck. It doesn’t have to be real tight because no force will be applied to it. Clamp the drill to the bench so you can hold the brush in one hand and support that wrist with the other hand. Rotate. Takes a bit of practice but if you mark up the object first with a faint pencil (spinning in the chuck) and use a good quality brush that doesn’t flare out it’s good for doing lotsa rings without all that pesky masking tape. Don’t overload the brush with paint & practice on something that doesn’t matter first to get the dilution right, so that it goes on evenly for enough rotations. Should only take a second or two per ring