It's string-like things that twang: well, long things, anyway.
Could you produce a twang by running a spoon along some metal railings? I suppose you might if they were made of hollow steel, but you'd probably only get a rattle if they were made of cast iron.
Something needs to vibrate audibly for a while for it to twang, and who knows just what will do that?
The only way to find out is to try it.
But that's the thing with twanging: there's a huge human desire to twang things just to find out what sort of a noise you're going to make. Who has never been tempted to twang a guitar string, or a harp string, especially if it's not actually yours?
Who wouldn't love to hear a bow string twanging beside his ear as it shoots an arrow? Who has never trapped a ruler in the flap of a desk and twanged the free end?*
Who has never wanted to try out a jews harp?
By Krzysiu - Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=63371399
The desire to twang things is a very mysterious but irresistible part of the human condition.
Go on. Give into the urge. You know you want to.
I mean, you must be able to find an egg slicer or an elastic band somewhere.
photo by de:user:Rainer Zenz
Thing To Do Today: twang. Someone made this word up in the 1500s in imitation of the sound.
*That would be everyone too young to have had a proper desk, poor things.