Flora is confused about why Ruby isn't leading this when she's the prefect. She will not be a very GUNG HO leader, so much as she will be very organized, take notes of everyone's ideas, and try to get everyone to settle on at least some sort of theme (that is nothing to do with fruit salad, Dae-Ho) to minimize the random things that are put in.
Her daily life is 100% free of Muggles; she's exposed to them at King's Cross, and maybe one other time a year at most, I would wager, so this is much closer to normal life than fantasy, for her. Someone else is going to have to come up with the central concept, and she is looking at you, Lance and Ruby.
Luckily for this group (or unluckily, since she probably will want to re-do shoddy work), she has spent her whole life being schooled in arts and crafts bullshit for Fine Young Ladies, so, creating tiny figurines will be right up her alley. She will want this to look like a tiny Renaissance masterpiece of clay and paint and textural elements, rather than popsicle sticks, tape, and sharpies.