Tool for "half circel border"

[Ray]

Howdy,

I am looking for a tool to cut half circel borders into leather like this:

https://img0.etsystatic.com/000/0/5804753/il_570xN.319728882.jpg

Anyone an idea where to get those punches?

Best regards
Ray

[Marshal Will Wingam]

I've just used a camouflage tool to cut the border then background outside that. It wouldn't be hard to make one from a bolt with a round file.

[R.T. Rangebum]

I took an inexpensive hole punch and ground away half of it, then polished. Works like a charm.

Rangebum

[Biscuit Joe]

The tool is called a half round punch. They come in many sizes.
I have heard it call a pinking punch when it's that small or used on a edge. 

[Ray]

Howdy, "pinking Punch" is exactly what I am looking for 
Thanks a lot 

[Buck Stinson]

You can make a pinking punch  by simply  figuring out how large you want the pinked edges to be and then buy a round hole punch to match.  Put the round punch on a grinder and cut it in half.  I've made several of these in many different sizes and they work as well as any specialty made pinking punch you would pay $45.00 for.  Make sense to me.