There’s loads of companies out there to contact:
Tuki CoversSpeaker WorksIf I were doing this, I’d head over to the local fabric store, pick out something that worked with the room/wife, some batting, some interior liner, and go to the bulletin board/store owner and pick out somebody who does furniture type stuff (cushions, pillows). Give them the dimensions (even a cutout to accommodate cable) and have something that’s a bit less industrial.
My fear with kids is that they’d be lulled into a false sense of security, and you might find that fabric doesn’t stop baseball bats or darts very well the next time you pull off the cover! YMMV.