It's sooo simple,,
Full or empty.
Go to a carpet/flooring store and ask to buy a hard center cardboard tube from a roll of vinyl flooring, cut into 6" long lengths for US qts, 7" for imperial qts., wrap the can in plastic or newspaper and insert into the cut tube. If still worried about it you can wrap the tube in bubble wrap.
Easy Peasy...
For those of you who have bought cans from me, you know my packaging techniques. I do what Dave said, then I wrap the tube in bubble wrap, then I put it in a box with foam peanuts. I’ve never had a can get damaged.
I get my tubes from a carpet store and cut them to length on my saw.
-Steve
