Many years ago, I had a friend who had invented some sort of an easily removable cap for pickups. As I recall he called it a Compacta-Cap or something like that.
It supposedly could be removed by one person and folded up for easy storage.
He seemed pretty obsessed with his quest to get this invention of his to market, in fact he became almost unbearable to be around as when you'd see him he'd immediately start talking about his invention nonstop, and how he was working with patent lawyers to patent his idea and meeting with companies trying to get someone interested in manufacturing and selling it.
I lost touch with him, but never recalled seeing anything in the way of his truck cap ever being sold, so apparently his passion/obsession with this cap he'd come up with never went anywhere.