If possible try to find chrome tanned leather. It is tough and hard. Skive the ends with as long a taper as you are able. Use flexible long cure epoxy or urethane adhesive. After the ends are joined they will need some reinforcement. I like to use tyvek. The mailing envelopes that the post office provides free are a good source. Two pieces laid in staggered to avoid a bump. Because of the skive it will be one way only. I would expect you will need two or more pieces of leather to get the length. I do this for lapidary belts but the belt grinder likely puts more stress on the joints than I do.
