For my part, I can offer what I myself have tried. I bought a laser marker and do custom engraving on leather goods. 1. they become unique. 2. you fulfill the wishes of the customer. 3. the product grows in value.
Instagram/FB/Tumbler could be a great thing for you to start you business. You can write articles and then sell your product. Moreover, I suggest to you get a great laser cutting and engraving machine.