@Kuroki: I was really looking for something anime or video game inspired, so I'm avoiding turning such a neat bottle into a simple vase.
@Bisected & PrincessKaori: I thought of a fairy too, but the opening/neck of the bottle is really small. Do you think it'd look funny if the fairy was so tiny? As I recall...weren't the fairies kinda large in relation to the bottles?
@generally everyone else: So...silly question. If I make a potion, any suggestions on what liquid or material I should use so that the thing doesn't gain mold if I just leave it on my desk?