EDIT - Some corrections to the background
I have a fondness for characters just going about their business when transformation nonsense happens. I'm pretty sure that's a more uncommon fondness, but I do.
I also have a fondness for calling things nonsense.
An Extra Step
The voted upon sketchbook only called for Rhoda and Lucy to grow and shrink respectively, ending up the former height of the other. I had imagined this being a more dramatic difference than it was, and decided the sketchbook needed a step further while still including what was voted on as the middle step (it WAS voted on, after all).
I also wanted an excuse for the size change, and I liked the idea of Rhoda reaching for something, but I found myself not wanting Rhoda to be responsible.
A POTENTIAL canon character. We'll see if she winds up in the main story. If not, she may still make future appearances in non-canon.
Her color scheme wound up being inspired by Magic: The Gathering card colors, of all things. Blue spells weakening creatures, and even specifically shrinking them, are common, while Green spells that make creatures bigger are VERY common.
Basically, she made me think of Blue-Green deck. I felt that was as good a reason as any to go with an analogous color scheme with blue and green on either end, and to color her magic as such.
As for the floating jewelry? I was trying various accessories, sketched those, thought "that was neat," and eventually thought having them change colors when she's doing stuff would also be neat.
It was all very carefully planned around the "that's neat" principle.
As per usual, the most difficult part about this sketchbook wasn't making it. It was getting over the intimidation of making it.
When it comes to comic, I can be a like a big dog scared a barking puppy sometimes.