This one from @theeditorialnail was definitely the most difficult to pull off — everything was fine until I got to the black lines! I opted for a more muted shade for the yellow-green, specifically J.Hannah's Nailpolish in Miso ($19). To make the large circle, I used the flat head of an extra-large nail. For the smaller bottom dot, I used Orosa's Pure Cover Nail Paint in Onyx ($12) and a bobby pin. Before you make the line, make sure the polish you've already put on is close to or almost completely dry or else it's likely to smudge. Once you're ready, dip the edge of a paperclip (or toothpick or bobby pin or safety pin) into the black polish and carefully make the line.
Image Source: @theeditorialnail / Aviel Kanter