This method has worked for me over the years, it works for any size or shape. I needed a small buckle for a horn strap so I figured I'd take Pix along the way. It is about 1 1/2 X 1, made for a 9/16 strap.
I 'm not going to label the Pix but just do a brief explanation first. Should be fairly easy to follow.
First Pix, this is what I started with.
Rough cut and roughly penciled in.
Set up in Drill Press vice with Pilot holes drilled.
Used a 1/2" bit and started filing.
Holes roughed out.
More filing, getting close to shape, grove started for Tongue.
Shaping the Tongue, I used a small nail.
Tongue rough fit. At this point I bend the plate cut a bit, a bit of a curve.
All filed and trimmed up. No finish yet but it will be Browned.
Tim C.