Does a Patronus take form of an animal only?

Question

So far what I can remember from books, I have encountered Patronus of a form belonging to Animal Kingdom only. Here's the list:

• Harry Potter / James Potter: Stag

• Hermione Granger: Otter

• Ron Weasley: Jack Russell Terrier

• Albus Dumbledore: Phoenix

• Lily Potter / Snape: Doe

• Ginny Weasley: Horse

• Luna Lovegood: Hare

• Nymphadora Tonks: Jack Rabbit

• Remus Lupin / Nymphadora Tonks: Wolf

• Minerva McGonagall / Dolores Umbridge: Cat

• Kingsley Shacklebolt: Lynx

• Arthur Weasley: Weasle

• Cho Chang: Swan

• Seamus Finnigan: Fox

• Ernie Macmillan: Boar

• Aberforth Dumbledore: Goat

I know that a Patronus is unique to a person and it can change because of emotional upheaval.

But, what exactly is the rule of creating Patronus form? Can I create a Patronus of a form X-wings or R2-D2 or Millennium Falcon or USS Enterprise-E or TARDIS?

Answer 1

According to Rowling, corporeal Patronus' are animals. If you want to be pedantic, you can argue that incorporeal Patronus' are non-animal Patronus'. But as JKR says, if it's a true Patronus, it's an animal.

The Patronus is the most famous (and famously difficult) defensive charm. The aim is to produce a silvery-white guardian or protector, which takes the form of an animal.

[...]

The incorporeal Patronus is not a true Patronus and while it will give limited protection, it cannot provide the defensive power of the corporeal Patronus, which has the form and substance of an animal.
_{Patronus Charm by J.K. Rowling}

^{(emphasis mine)}