Leather is a great product to engrave upon. I took our 3 1/16" leather rounds and made medallions for my son's baseball team. It was a neat end-of-season surprise for them.
I first created the jig out of an alder sheet so that I could engrave more than one at a time. This DRAW file contains the layout for both the jig and the baseballs.
For the leather, use a paper mask for vector cutting. Cut at 1200dpi. With a 50-watt I used P=100, S=10. Remove the mask and raster at 600dpi, P=65, S=100. Then I added a leather neck strap.