Lego introduced minifigs based on the four founders of Hogwarts in their recent castle set:

[![enter image description here](https://i.stack.imgur.com/1C4cC.jpg)](https://i.stack.imgur.com/1C4cC.jpg)

Considering the characters have never appeared in either the movies nor the books, and knowing Lego's propensity to keep details as accurate as possible (particularly in adult sets like these) on what did Lego base the character's appearance?

(I'm obviously excluding the basic male/female attributes.)