I have used these for geocaching, i have used these as is and also modded the idea with magnets for magnetic caches.
I glued the two haves together, to make a tube, turned it on end on a bit if card, driped adhesive into the bottom, left to set, then rubed the end down, drilled holes in the end for the shaker,
So i could undo the bottom for refiling, and use the other top as a top...
I did think about putting a bit of plastic between the two, so to have a salt and pepper combo. But liked the idea of each shaker having lids to stop spilage.