Model sheets for the characters' designs from the series artists' guide.
I'm sorry I don't have full figure sheets for all the characters--I bought these pages as an auction lot and knew there was a chance it wouldn't be complete. I'll keep looking!

Click on small images to see each page in larger size.
(In case you wonder, the purpose of the first piece is to show all the characters' relative heights to make sure they're always drawn in correct proportion to each other. I hadn't realized that Thobari-sensei is the tallest one in the cast. =)

(Note that the "Banten" crest on the school uniforms is rendered "Bang Teng" in the sketches.)