Sorry about the DiC music! Finding music for YouTube is such a pain, but these brooches aren't.
They come out of the box fully assembled. They're a little more than 2 inches each. I highly recommend this Compact set, featuring four of Sailor Moon's brooches from Bishoujo Senshi Sailor Moon, R, S and SuperS and Sailor Chibi Moon's SuperS brooch! They are way more sparkly in person and have a flat back, so you can affix them to any costume using tape or glue. They can open up and be used as tablet or trinket lockets.
Earth-chan is very much in tune with her inner child. She spoils that kid, too.