I worked out the pattern from an old top of Thomas' with some modifications, and making it much smaller. The wraps are secured with a press stud on the outside and a button and elastic loop on the inside. I'm pleased with the result and that I used only stuff we already had, some organic cotton I'd bought ages ago, and I made some bias binding from a Japanese chirimen cloth - one of several I'd bought in Tokyo years ago and have been hoarding ever since.
The only downside is my dodgy sewing skills, so that up close the stitching on the slippery bias binding leaves a bit to be desired, especially on the back. Anyway, it definitely has that handmade touch!
Here it is all wrapped up and ready to go.