Bullet cufflinks are nothing new. We have covered a bunch of them here in the past. You don’t always have to check sites like Etsy to find these things though. DIYgiveaways has published a guide that shows you how to create your own bullet cufflinks using bullet casings:
You are going to need two .45 caliber bullet casings, 2 x 12 mm cufflink blanks, and some glue to get started. All the parts and tools are covered at the link below.