The Death Star looks works really well in crochet:
Image source: http://popsdemilk.com/ which has lots of good crochet ideas.
And if you want to be up to date, here's a YouTube video of how to make your own BB-8 Droid hat:
The latter was posted, a bit diffidently, on a Facebook crochet group by a bloke who ended up being rather overwhelmed by the approbation he'd received; he seemed a tad nervous that his creation was left-field to other projects being posted.
For more, any search on "Star Wars Crochet" on Ravelry or Pinterest would be bound to hit paydirt.
I asked one of my nevvies if he'd like a BB droid hat crocheted by his dear aunt. He hasn't responded, which could well be a response anyway....
UPDATE: but another one was very very very keen....