I wrote to Buckle Guy and this was the answer that they sent:
Thanks for reaching out. The leather itself would be great for wet molding, but that would be a pretty thin weight. We would recommend either going with a thicker option, or at the least, adding a second layer of that leather.
I’m leaning with @Heartless (at least for the first couple) since it’s a new mold and I want to take some of the variables out.