I had always assumed it was some kind of grounding block?
3 plugs on a block sat on a grinding disk to me
they have a metal thread, screwed into a threaded hole in the solid brass, so no.Are all the connectors insulated from each other?
It is solid and the disc, cable tie and metal rod are not involved.Three terminals on a box isn't going to reveal its purpose unless you open the box to see what's inside. It could be absolutely anything, though most likely the red and black sockets take a dc power supply of some sort. Perhaps it's got a voltage regulator in it, with a regulated output on the green terminal.
I'm assuming the cutting disk, cable tie and bit of metal rod aren't part of the puzzle