Here's another one:
I had an issue with bruxism (teeth grinding) and so years ago I got a custom mouthguard made to wear while I sleep. Custom molded to my teeth, it cost several hundred dollars to get made.
Recently I dropped it on the floor by accident and it cracked into two pieces. It still works, I just need to place each separate piece onto my teeth and clean two pieces the following morning instead of one.
I had been wondering though (both for this reason and if/when this mouthguard eventually wears out), whether the same functionality could be achieved by a generic martial arts/sports mouthguard, and if there are any pros/cons I should be aware of about this alternative idea.