he is referring to a media blasting, or "sand blasting" cabinet.

This is an enclosed space, generally a little cabinet with glass type windows, into which you can place objects (generally metal parts) and reach in with rubber gloves, and manipulate a high pressure tool that directs pressurized air and some type of abrasive media. Usually, tiny glass beads, sand, or other products that have finer or larger grit sizes and more or less aggressive abrasive properties.

What you are trying to do is to gently take off (or sometimes aggressively take off) whatever is on the outer surfaces (like rust, coatings, paint, etc) to get it down to either bare metal or another desired surface.