I use the ends of two small wooden paint brushes. One larger than the other for the big eye. I also have sanded the ends of the paint brushes flat just a bit.
Not perfect, but works fast and the end result is good.
I lay all the jigs flat on table, then dab paint off of paper plate. Can work really fast. Wait about an hour between coats and then flip over.
MY last batch was 300 jigs, so that was painting 1200 eyes. I opted for speed over high accuracy
Good luck!
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