I started in the centre with some scroll-y Flux shapes then worked out from there.
I had to laugh at myself when I looked at my final scan just now because I noticed that I started off shading in cool grey, then today I've must have picked up warm greys to finish off. We're just going to have to pretend that it's intentional and that the "warm" part of the design is reflecting a bit of sunlight or something - I won't tell anyone if you won't ;)
Have an amazing weekend! Mine will be busy with lots of homework.