See title

Just so you know what to look for - It's possible to do it as a tattoo box (but I haven't seen any piercing ones).

As regular makeup (the kind you apply in CAS or in the makeover screen) it isn't possible, because only makeup that covers the face area is possible to do.

Would it be possible to do one as jewellery or accessories? That makes the most sense.

That too would be possible. Maybe a bit less practical since you'd always have to pair them with tops that show the belly, since they'd poke through anything that's close to skintight. Probably more practical with a jewelry version since you can set it up with different outfits. Then there's morphs and other things to consider (I don't think accessory versions would work with pregnant/fat morphs, or you'd have to make separate ones for that).

Also, skins don't always come with the bellybutton in the exact same place, so both texture and accessory versions could end up being a bit hit-and-miss depending on which skintone you go for. I think that's why they're usually painted onto skins, or why a tattoo box is probably a bit more practical.

For reference, a bellybutton piericing overlay box exists since last year:
https://themeasureofasim.tumblr.com...time-with-navel