Maybe a small cotton canvas rucksack like this, that you can find in surplus stores and thrift stores. No breaking zippers, extra cordage from the fastening cord at the top. You waterproof it with a small dry bag liner or something.
WARNING & DISCLAIMER:
SELECT AND USE OUTDOORS AND SURVIVAL EQUIPMENT, SUPPLIES AND TECHNIQUES AT YOUR OWN RISK. Information posted
on this forum is not reviewed for accuracy and may not be reliable, use at your own risk. Please
review the full WARNING & DISCLAIMER about information on this
site.