Fastback rear speaker boxes

Lol, I just found the "terminal cup" on Amazon.
Funny no Radio Shack up here anymore and they used to have ALL SORTS of that DIY kinda stuff....sad.
They make that stretchy speaker box material you can buy on Amazon. Works pretty good.

You can also buy a wide variety of connectors on Amazon. That’s where I buy all my electronic supplies now. Sometimes it takes awhile to figure out what it is called when you are looking for something.