I don't want to confuse the OP, and people who have seen some of my posts about files will know that I'm a bit of an old woman/got a bit of a bee in my bonnet when it comes to not allowing files to clang together. BUT....... I'm sorry to say that I completely disagree with the above posts by both MikeG and D-W.
In my opinion (AND as per what I was taught in a decent apprenticeship), files should NEVER be allowed to knock together - not even gently !
WHY NOT?
Despite what D-W says about the steel used to make files, and whatever the steel spec and the after-cutting heat treatment, etc, that may be used to create the finished file, the result is ALWAYS a piece of metal which is about the hardest piece of metal you're ever likely to come across in the average workshop - certainly in hand tool terms anyway.
And the general materials properties "rule" applies here - hardness = brittleness. Just to reinforce that general point, how hard is the average piece of wood compared to the average piece of glass? And which of those is the most brittle?
So allowing two hard (and therefore pretty brittle) pieces of metal to clang together, even gently, WILL result in damage to whichever of the two are slightly "softer", or more likely in the case of files, a file with a very sharp tooth form will get EASILY damaged if banged even gently against another file - Yes, even if you "shut the drawer" VERY gently!
For more detailed info please check out the sticky posted in the General Metalworking section to see some ideas about storing files (it's a long post, sorry, but there's a fair bit of files and filing info there):
files-and-filing-t108361.html
Amongst other things you'll see pix of some pretty coarse-toothed files in that post, and I can definitely guarantee you that if you just store them loose in a drawer (or anywhere else) without any protection between their cutting faces, then teeth WILL get damaged. That's a 100% certainty.
So what if teeth do get damaged?
Well as I also say in the above-linked post, although they may not look like it at first glance, decent quality files are not only precision cutting tools (if used correctly), but they're also pretty expensive these days. Personally I want to protect my "investment" (even if only inherited from my Dad, or bought as a cheap job lot at a car boot sale). Files with a chipped tooth will make the job of producing a quality result harder - if not impossible.
So if you want to produce the best quality precision work like I imagine D-W does when he makes his planes, you definitely do NOT want bits of teeth chipped out of your files - especially not if the chips are "only" because you've allowed them to clang together!
Frankly I just cannot contemplate treating tools in such a cavalier fashion. And although I may well be more than a bit pernickety than most when it comes to files, I know I'm not the only one.
So if you're talking about storing several (or more?) files in a workshop, then the ideas posted above are all workable it seems to me. What anyone does depends to a large extent on what suits each user personally - corrugated cardboard; a wooden base with slots in it; bits of plastic pipe off cuts; anything you like really, as long as you NEVER allow files to clang together (any more than you should ever allow thread cutting taps to clang together - another example).
And as also said in that above-linked post, even if you're only taking a couple of files to an on-site job on a "just in case" basis, if nothing else, a couple of bits of newspaper wrapped around each file will definitely be better than nothing.
For my own storage ideas, the above-linked post shows that some files in my collection came in "pretty little" plastic pockets - which I think are fine for protecting files as long as they last. And I've also shown what I've done for singles, making some very crude "chisel-type/tool rolls" out of fabric, hot glue, and office staples. For my bigger files you'll also see a drawer in my tool chest which I've "lined" with foam plastic - it's just a cheapo backpackers' sleeping mat, cut to fit the bottom of the drawer, with additional narrow strips of the same stuff simply laid on edge between the cutting face of each file (which are also laid on edge in the drawer - but note that I have very few files with permanently fixed handles. If you have permanently attached handles you'll need thick foam between each file).
But whatever idea you actually use is, IMO, MUCH less important than simply making sure that files cannot clang together.
Finally, although these days I'm lucky enough to have a workshop in the basement (cellar) of my house (where I have zero rust problems), I've previously used various outdoor sheds etc, in the past (including when living in Singapore, which has a VERY humid climate). In all that time I have NEVER had a bad rust problem with files stored in any kind of "tool roll", home-made or otherwise.
So I disagree with D-W when he says that files are prone to rusting - not in my experience they're not - or certainly not all that much when compared with many other bare metal surfaces to be found in the average workshop.
But if you do find a bit of rust on a file, removing it is just about the easiest job ever - again the post linked to above will show you suitable, widely used file cleaning/de-clogging "brushes" (which should BTW, be used after the file is used each time anyway). And if all else fails then the electrolytic de rusting bath (see Youtube) will solve all your rusted files problems literally over night (ideal for those worthless-looking crudded-up files you bought in a cheap job lot at the car boot sale/flea market).
That's my take anyway, HTH.
