Here is one being held by the Fourth Doctor (a custom minifigure by minifigs.me). Yes I know his sonic didn't look exactly like that, but let's face it, neither did Tom Baker.
I hasten to add, these did not come to me via the CEE team who will be sending out the review sets in due course. Mine fell off the back of the timey-wimey equivalent of a truck a few weeks ago and with the first review of LEGO® Ideas 21304 Doctor Who now live, I figured it was safe to let them out of the Pandorica.
Admittedly there isn't much to say about this part which you can't discern from the above image. It is made of Warm Gold [TLG]/Pearl Gold [BL] plastic with green and white printing and is beautifully detailed. It is 19mm long, which is between two and three studs. The solitary point of connection is the 3.18mm bar section of the shaft, above the white printing. I can't find a Design ID printed on it and feel it would perhaps be excessive to disturb Huw on a Sunday to have him look up the Element ID in his instructions. (He did anyway, yay Huw! 6122423)
With so little to say about it, I decided to see what Doctor Who fan (the proper old ones, not NuWho) and occasional LEGO builder Pete Reid might make of it, literally, and set my coordinates for deepest, darkest Romford.
Having enticed him with some electric eyes (not her own) Pete plucked the embryonic robot from Yvonne's hands and completed it rapidly, crowning it with a fez.
Turns out this chap is actually the 11th Robot Doctor from Alt. Universe Epsilon 86, as featured in an exciting adventure by Alt. Terrance Dicks, which coincidentally Alt. Pete once novelised.
"The 11th Robot Doctor (M4-TT) and his companion, Frobisher, arrive on an apparently deserted space station..."
21304 Doctor Who is released on December 1 priced £49.99/USD $59.99/DE €59,99. For more Target novelisation covers from an alternate reality, check out the Off Target group on Facebook.