“Rings” were a popular suggestion for non-Moon transformation item alternatives, and I really like the idea; they’re small and inconspicuous, and you can wear them anywhere without needing a place to keep them. So, here are some design ideas for what they might look like.

Mars’s design is based on the brooch that appears on her waistband in the manga, though upside-down here for comfort. Jupiter’s is obviously a rose, to match her earrings; Mercury’s, aside from “bubbles”, are based on her manga earrings as well. The band gradually increases in width at the back of the ring. Venus’s design is taken straight from the Holy Blade, the sword from the Silver Millennium she wields in the manga.

Pluto’s design is a sideways stylized Garnet Orb with a band inspired by a key. Saturn’s is based on her amulet from the manga - the gem in the middle would be a lot taller and protrude a lot more than the others’. Neptune’s is inspired by her Deep Aqua Mirror from the manga, and her Anime lip rod; Uranus’s is also inspired by her Anime lip rod and her Space Sword.

(These guys are not to scale with each other.)

Edit: Changed Jupiter’s to reflect the better, initial idea I had - to put more of a focus on the green gems reflecting her Leaves of Oak/wreath, and make the rose a smaller focus - but which I for some reason completely forgot about when I was actually drawing them. Old design