I applied two coats of Models Own Baby Blues for the base then let it dry. Then I put some Barry M Matt White onto a piece of cellophane and used a nail art dotting tool to create the clouds. After doing a 'practice' cloud on the cellophane I was good to go. So off I went and it was SO EASY, literally just dotting about the white polish to look cloud-like, then finishing with a clear top coat. Take a look:
I found the nail art tools on Amazon for only £2 so snapped them up immediately. There are five different sizes and I used the biggest one here which was perfect for my purposes.
Nail Art Tools - Amazon