Holder for brillo sponge / inox pad to keep your soldering iron tip clean. I made it a bit taller than needed, so you can put some metal nuts and bolts (or sand) in the bottom to give it some more weight against sliding around. (rubber feet will help too) note; Since normally support material is only printed with overhangs aboven 45/60 degrees, it does not cover the whole cavity, so removing is a breeze