i realize this is a baby bonnet, and I don't know any babies, but this is just uber cute. Corinne's Thread: Baby Sunbonnet - The Purl Bee - Knitting Crochet Sewing Embroidery Crafts Patterns and Ideas!
DIY - How to Make: Doll Joggers -Handmade - Clothes - Craft - 4K
Baby Bonnet, 1911 measure and compare this with the desired size before cutting fabric. Once you have a size that works I think would made an interesting template with which to apply other embroidery designs.