Heavy water.
Snob !I use a piece of wet chamois leather..
Its about 30 years oldSnob !
Heavy water.
Small neodym magnet on top
Good idea but I think that the tray is aluminum.
Heavy water.
Use a large neodymium magnet then.
I only recently discovered that's actually a thing!
Glue another magnet on the underside of the trayGood idea but I think that the tray is aluminum.