Transcribing from any number of texts you read offers the pagan a means to not just add something personalized to their Book of Shadows, its also a lesson in learning.
I find if I copy down what I read, I tend to remember it more later. If only my handwriting was nice, so I figure it counts if I retype something in a handwriting font and print it out for my book. This also provides some consistency to my Book of Shadows.
You might also add journaling spots in copywork, so you can add your own notes, quotes, thoughts, or even sketches that inspire you.
Just remember to also add where you copied the work, who the author was, and respect their copyright.