Actually, it is (or at least, WAS) sold commercially.
https://www.eham.net/reviews/view-product?id=552
I can’t remember where or when I got mine - possibly at the Dayton Hamfest in 1999? The links I’ve found for it don’t appear to work. Construction involves gluing strips of thin brass for the contacts.
…watch out - if you follow the links it will lead you to a x rated site
That particular link doesn’t, but some of the links on the page may do so.
A bulldog clip paddle using a small block of wood and some copper strap and buttons… that’s the kind of genius household inventiveness I’m used to seeing on VK3YE Peter Parker’s Youtube channel!
…just checked again, the link for “..more information” is to the x rated site
It’s actually a very ingenious design and very practical 
It took a whole day to think about Bulldog! How does it work?
It took only 10mn to build it !!!
Watch “Dingo CW key” on YouTube
