I trooped with a TK.
A delightful young man who is an R2 Builder brought his R2-M5. He said he built it like a tank so the kids could mess with it to their hearts content and not do much damage.
He was assisted by library volunteer Alex, who is himself a roboteer (at left). He's the chief engineer of his high school robotics team. Yay!
The librarians recognized my costume right away as the "Jedi Librarian". They asked for this pose specifically: