I'm not a hoarder (though my wife may feel differently), but sometimes when I come across a material, I just know it will come in handy SOMEHOW down the line. And often when I chuck stuff I don't have a use for, I later realize that it could have come in handy.
I thought we could try to come up with uses for various items that don't have an immediately obvious purpose in the shop and might get thrown away, only to be proven useful down the road in some capacity.
This is a bit of an experiment, but I thought the thread could work by posters listing various junk/scrap material they have around the shop and seeing if others have found uses for it.
I'll start:
styrofoam (e.g. from packaging)
short lengths of pipe (EMT, brass drain, etc.)
carpet underlayment/foam