In reply to ColH72:
I found the old Grivel envelope style crampon bag (like the Alaska one linked above) fit my 2F crampons set up for size 10 boots without collapsing them.
I've since upgraded to a Grivel crampon safe which fits terminator crampons (which also will not collapse nicely. The mesh top lets them dry without rusting too.
My 2Fs now live in an old heavy duty alpkit dry bag.