To my understanding, 304 designates the most common grade of stainless and is not surgical steel. While stainless alloys that contain molybdenum (etc.) would be designated as surgical grade and have a higher resistance to chemical destruction, I don’t think it’s a necessary precaution. I have an aluminum pill fob that’s had the same dmt in it for going on eight years, and there don’t appear to be any signs of corrosion whatsoever. If you do store freebase for this long, it will likely polymerize (and turn red) over time, as my sample has. Fumarate is reputed to be better for long term storage. But take all this with a grain of salt, as I’m no chemist either.