I use Aunt Martha's Ballpoint paint tubes.
https://www.google.com/search?q=aunt...=silk&ie=UTF-8 . You can get them from Joanns, Hobby Lobby, Amazon, ect. I really like them for quick features on dolls, quilts, and quilt labels. So far I have never heard of anyone else using them on quilts, but I've had very good luck with them. This baby quilt was made using them and it has been washed countless times now and still looking great!
https://www.quiltingboard.com/member...36-577690.html