There are a couple of different processes used for delivering blast media. All the small blast cabinets, I have seen, use a syphon feed system and have venting and vacuum evacuation for the air/dust. In this system the pressure would be confined to the hoses within the system, and there would be no "pressure" developed inside the cabinet. This cabinet structure need not be overbuilt, with 16 ga being adequate for a hobby unit. In larger, more powerful, units the media is loaded inside a tank and pressurized to be forced thru the hose to the nozzle. In this system, the tank must be constructed to withstand the internal pressure and the weight, plus wear and tear from media. The cabinet or "blast room", of the pressure feed system, can be subjected to a more severe pounding from the media, so it too must be of much heavier construction than the syphon system cabinet, however the design of the cabinet/room is such that minimal interior pressure is involved. There are also systems which use spinning wheels to hurl the media at the parts. These must be constructed of very heavy, abrasion resistant materials, but these are not found in the average garage.