These cufflinks are made from actual fired 7.76mm cartridge cases, and are, I suppose, limited edition (in that 20 sets were made for sale, for charity, and sold to friends). Although they can definitely be described as 'novelty' in the most obvious sense, they are probably understated enough to be unselfconsciously worn (if you're the sort that is concerned with such things, which I don't recommend). I think they are a superb idea - and not very difficult to actually make for yourself if the inclination, resources and time happened to favourably coincide.
I personally approve entirely of unique, outlandish and downright louche cufflinks. They are, after all, the most subtle yet permissible subversion we are allowed within the man's uniform. As I am not one for pocket squares in any shape or form (except perhaps a simple white square on very special occasions), and my ties are broadly conservative (stripes, paisleys, one or two tartans, one or two solids, one or two polka dots), cufflinks are really the only outlet of individualism I have left myself. As a result, I enjoy them to the fullest extent, and propose that you do the same.
"Nicky Haslam says cufflinks are common. I don't listen to him. He says everything is common. I think it's common to say things are common."
- Jeremy Hackett