Some come in cardboard, some in plastic and some in steel cans. It all depends on what they are, the size package and who they are from. For ex: Linc 6010's are available in 10# can...I believe they used to have a 5# can, too.....and a 50# can. Hobart 6010's are in one pound plastic tubes, 10# plastic can/tube deal and 50# can. Switch to 6011's and the big cans are now cardboard boxes. I don't believe there is any rhyme, reason, or logic behind any of it. It is all just a ploy to keep us guessing.