Although an advocate of trying to make everything, it is too easy to buy something like that especially when the little thieticle has not changed much over several centuries. When you attache it, keep an eye out for a couple of things;
watch the base part so it does not scrape your knife ( or pistol) when you draw it out. Metal studs have a tendency to do that.
Also...and obviously...you have to put this in place before you do your stitching, so you gotta estimate where it's gonna go. Leave a little extra on the strap.
Lastly, the hole in the strap will be basically a hole punch and slit. Try not to make them any bigger than is necessary else they will come undone on the trail.
Don't shoot yore eye out, kid
The Capgun Kid