I don't shoot and indeed have never done so and have had to source some empty shotgun cartridges for this easy project...As well as a source of spent shotgun cartridges you just need a heat source, a pair of pliers or similar and a pair of scissors.
There are several different types of cartridge shape and arguably the best known use for a shotgun cartridge container is a match holder for which the cartridge is a good size to use but it's not it's only use...
For the match container I've picked out two similar cartridges (but it's worth remembering that all cartridges have the same diameter) in good nick and marked the casing on one a little higher than the match being held against it. Once marked, cut out to the line. With this particular example I cut it to the upper edge of the line but more on this later.
Once trimmed you can place it upside down on your hand or a flat surface and check that the cut edge is smooth and level. It won't necessarily affect it but it doesn't look good. Once you are happy, gently heat the brass head of the other cartridge with a small flame, I'm using a hob but this can equally be done with a small fire.
Take care not to melt the plastic casing and after a short while try the brass head with a pair of pliers or in this case a mole wrench and when it's ready it will gently slide cleanly off.. Once the brass head is cool enough to handle (and be careful what you put it down on to cool) you can then offer it up to the trimmed end of the first cartridge case and it should fit snugly on, this is the container's lid.
The reason for allowing a little extra when cutting the plastic casing down is evident in the left hand side picture (above).The priming pin in the brass end extends a little way into the cartridge and will potentially snag on the matches making it hard to put the lid on. Remember if you use safety matches you'll need to include the side of a matchbox in the tube!
Easy peasy isn't it? Using the same technique as above, trim a cartridge down near the bottom leaving a plastic container about just a little deeper than the brass end. Remove a second brass head and use as a lid like before and you have a handsome little container for lip balm and indeed any sort of ointment I guess.
And finally a container made from a cartridge that has a larger brass end. This cartridge makes a container about the same maximum size as a cartridge with a smaller end. This size end feels very secure. Just a note on the bigger (and to a certain extent the smaller) brass ends, you may find a little plastic residue left in the end depending how it's heated and pulled. You can see in the picture of the two ends that the left hand side one has some plastic left in whereas the right hand side one is cleaner.
And if you'll excuse the pun, a shot to finish of various different colours and sizes, note the red one in the centre has a large and small brass end. I reckon anything goes as long as it's not foodstuffs (not sure if food and gunpowder residues may work) but matches, tinder, fishing kit, lip balm...