The tubes (tubos in spanish)come in a myriad of sizes, but most have a press fit
end cap with no seal except metal to metal, so they would not be absolutely waterproof.
The screw top tubes shown in the first post come with some Romeo y Julieta cigars from Cuba in two main sizes, both about 3/4 inch diameter - 4 and 7/8 long (Romeo #3)and 5 and 1/8 long (Romeo #2).
They both weigh 7 grams each regardless of length since my scale will not register 1/2 gram. Both tubes will hold waterproof matches stacked in two bundles one on top of the other, and are lighter that commercial waterproof match cases. The lid gaskets are real thin poly foam sheet so they will not rot.
Match case for one.
I am thinking of making my dryer lint firestarter wrapped around a thin piece of wire.
The case is filled with the firestarter with the wire in the middle. You pull on the wire to get the firestarter to the top where you can peel off a small piece at a time.
Simple and no plastic bags or litter involved.
The tubes are lighter than any small bottles for spices, sugar, salt,drink mixes, medications, or whatever you want to keep dry. The tubes will hold rolled up pieces of silnylon or cuben fiber repair tape in a case lighter than the commercial case, along with any glue tubes. The tubes will hold sewing or fishing kits along with a mini swiss army knife.
The fatter tubes will hold a 5 day supply of blue shop towel toilet paper or a complete mosquito head net.
Use your imagination.