I realised I need to by some more small hand files. But I have blocked out the basic shapes.
I cut these back to front, ideally and historically holes need to be drilled first then the outer edges so as to reduce sheering the fine areas while working them. But I used a heavy vice so it wasn’t that bad. Dremel with a router stand thing helped create a shallow line to use as a guide for the naked cutting tip. And a sanding tip was used to help shape. And a mouse sander for the outer edge being tidied.
The circular buckle is in fact wonderfully flexible and will not break on me despite being fairly thin and narrow. All buckles will be reinforced to allow them to be partially functional and used to disguise real fastenings.