This first example can get you started and it’s exactly what you’d need to do to make your stamp, but you’ll need an additional step of inverting your file so the image is facing the correct way when stamped. The example talks about using Inkscape, but it applies to AI too. (The commands may be called something different though.)
This has a ton of resources too.
This one is specific to AI
Here’s other discussions about making stamps and some of them are specific to leather.