This little trick has been noted on a couple of the machinist boards now, as well as a couple of the hotrodders boards.
It is indeed a cool trick, and one that I plan on using before too long.
But there's some caveats and drawbacks to it. As that thread noted, some foams go through the cloth, and as other have found- the hard way- in a few cases, the solvents given off by the curing foam have caused rusting or tarnish.
It's also, in my opinion, not the best idea for day-to-day tools. Note how much space is wasted in that example drawer. Sure, you'd have to pile 'em, but you could get three or four times as many tools in that drawer without the foam.
It'd be best saved for specialty tools, like your mics and calipers, rather than taking up an entire drawer in order to fit just one set of combination wrenches, for example.
As for the rust issue, that's true as well, if your local humidity is fairly high. I'd imagine you could spray something on the cloth though, an oil or preservative, maybe? Not sure how that'd react with the foam, so you might have to do some experimenting. Or use a synthetic cloth, rayon perhaps?
Or just invest the time in routering the necessary shapes into wooden inserts, which can then be sealed and clearcoated.