Like the springs gadget, I've not ever seen one of these things in the flesh. Sadly, I think that if a person found one of these things they would have no clue what it was. I don't hold out much hope that one will turn up for me to buy. Perhaps I'll put a want ad on the Banjo Hangout?
And... I would want the latest model with patent hinges for turning over music.
Y'know, with a very little modification this could be clipped around the neck. Most banjoists don't use their heads anyway, more blood for the fingers!
And hey, marching Banjo Bands! We'll take over the world! Buwahahahahah!