I haven't seen any Darth Vader castle projects as yet! Let me know what you think of my micro castle?
https://ideas.lego.com/projects/169210
Darth Vader's Castle from Rogue One in micro size. Its a simple and compact play-set with your very own "Bacta Tank", who doesn’t want their own Bacta Tank to detox in! It has a technic lever to dip Lord Vader in and out.
This set could be a great idea in gaining director Krennic, Darth Vader's servant and of course a Bacta Tank Darth Vader mini-fig(s).
Its a small piece count so would be very affordable....