It has existed in the past, but was attached to a very odd key/lock mechanism that didn't take off. It's a good idea, no idea of patent issues related to making

It has existed in the past, but was attached to a very odd key/lock mechanism that didn't take off. It's a good idea, no idea of patent issues related to making it happen, but perhaps with all of these recent stories on duplication the time is right to reintroduce the concept.