Hammer and marker can buy at any hardware store (or look in your toolbox). I don't think that a piece of this inox plate will also be difficult to find.
I find willi9974 set more a
collectible set than something I'd mess with. I may have odd taste, but the plate with the mount, the HOLD Hammer and marker seem to ask to be shown, not hidden away.
If I would ever have good reason to store the seed on steel, I'd probably go for the washers, really. Your setup looks complicated. And complicated usually asks for troubles (in 10 years, not now).