I collect it in a stone bowl(from a mortar, it's a heavy stone bowl that doesn't tip easily)
but that's just a tyemporary first storage, where it stays for a few days at most, then I empty it in a sandwichbag wich I keep in a small box, the size wich fits trough a mail box)
and if the sandwichbag fills up the whole box I get a new bag, the old bag I tape shut(just one piece of tape tough), and store it somewhere on my desk(wich is more a collection of all kinds of things, among others lots of papers, books, electrical cords, old broken headphones, empty candy wrappers, empty chips bags, change etc), sometimes I joke my desk has it's on tectonic activity, if I put something new on top of the pile something at the bottom falls of the desk.. altough that's more like a landslide, but I like the sound of tectonic activity more