My first thought when I put this together was, "What in the heck? Is this supposed to be a droid or something?" Turns out it's a mechno-chair.
Never heard of a mechno-chair? I hadn't either. You'll recognize it when you see it, though; it's the contraption that projects a hologram of the emperor (technically, he wasn't the emperor yet) while keeping pace with the real-life Neimoidians he is talking to. I'm not sure why Lego thought we'd want a mechno-chair without an Emperor hologram minifig, but whatever.
This thing is also known as a mechano-chair, but if you're doing a Google image search, "mechno-chair" brings up better results.