LOL...
Spend so much to get the filters and yet think that they are as fragile as ice cream cone waffles. :bsmilie: Then the best place is in the dry cabi... :bsmilie:
B + W filters, if not mounted on lenses, just carry in the plastic box that they come in. Unless you are doing a parachute jump with camera and stuff.
The same goes for Tian Ya, they come in a box. Not sure about Lee and Cokin.
Filters are not ice cream cones waffles.
If still afraid of breaking the waffles, you can try this
http://www.pelicancase.com/small-pelican-cases.html#1120. For best results, house the waffles in a pelican, in another pelican. But that the pelicans will probably cost more than the waffles. FYI, these cases are waterproof, airproof , fireproof and crush proof, for the paranoid