Painting question: creating unit cohesion with Roundels.

Does anyone have any tips on how I might create small consistent roundels (the circular colour symbols airforces use to denote their nation) on mech flat surfaces?

I’ll admit I get the shakes at times and hand painting detail needs to be done in chunks but I wondered if there was a strategy people might use. I know a lot of the classic military miniatures use decals and larger scale, however I was hoping to create something minimalist for mercenary lances with a particular affiliation. My colour scheme is a grey blue (losing some of the blue with the wash) and I wanted to incorporate some light green panels with a red-brown stripe but rather then heavily relying on these panels to create contrast I thought some small roundels would work well.

Suggestions more than welcome.