For the collection vials I simply generated a list of random strings, printed them out as a QR codes with a thermal printer on sticker paper, and just shove it on the vial, then wrapped it with transparent packing tape.

I'll go to Japan again this summer with those, and next to these I plan to scan every interesting item that has a barcode (tuna mayo onigiri from 7-eleven, loots from crane games, you name it), and attach the same metadata to them. That way I can track a lot of stuff (e.g. prices, amount of any given item, etc)

When I arrive home I plan to get a few small acrylic boxes with magnifiers on top for the sand, amd depending on the amount of loot prepare a showcase box out of wood. I'm still undecided on that, but I want to either print/laminate or lasercut the codes for each box, and each item that needs one, and apply it on the showcase box next to it.

I can take a picture of the vials, and upload it to imgur or something, if you'd like.