The Void, from season 5 of Clone Wars: R2, a new pit droid build for WAC-47 and 200 white plates (no tiles, so it just builds up to be two layers of plates with their studs visible). UCS version to follow, adding the other three astromechs and General Gascon - a similar size to the Palpatine hologram piece, so he can be stuck onto M5-BZ's head - and 2,000 white plates and tiles.