I've changed my idea for my animation, and decided against the AT-AT. I've been told that it would be too big and complicated for the time I have available, let alone trying to animate it. I should stick to things of a sensible size that I can get a good effect on, rather than spending all my time working on one huge model that will be difficult to both create and animate.

My new animation still involves R2D2 being awesome, but in a different way. Now, the scene is set in a corridor on the death star, with R2 chasing a mouse droid. It continues to annoy him, until he eventually overrides a door control and squashes the robotic pest.