First thing I must say is that the concept for this is not mine. It was originally from Bonnie Burton's Star Wars craft book Not owning the book I don't know exactly how this is made, but internet scuttlebutt is that the legs are pringles tins just stuck onto a herb planter with a fast food container as a head, all duct taped up. I like to think mine is better as I added the AT-AT shape to the body/herb planter and the legs are square.
Poppy trivia: the cardboard used in this (all duct taped up obviously for waterproofability) was from that big ol' box I got - remember this picture?
Materials: cans, cardboard, a skewer and 24.5 metres of duct tape.