I looked all over for grenade packing containers... couldn't find any.
I wound up making these from assorted sizes of cardboard tubing and end disks ... can't remember which supplier but it was either from Skylighter or Pyrocreations. I had to cut the tubing to proper lengths on a powered compound miter saw. Everything was glued together with Elmer's carpenter glue. Then the outside was spraypainted with black spraypaint.
The orange color on the inside is from wet paint that was on the end of a powder charge that was put in there before the paint was totally dry. The outside ends of the cardboard container as well as the end of the powder charge are color coded to tell me how much powder is in it. I put them in a 50 caliber ammo can with the same color painted onto the lid, and clear labeling on the can saying what is in it.
This one is for 2.25 inch bore charges, but I have made some for 1 inch bore as well.