girl at large

only an important errand would send me out into the blistering sun today…i need a large poster mailing tube so mom can bring home a number of my pieces as requested…
moi: excusez moi, svp, madame, je cherche un…un…um, continues like so in bumbling french: i need a thing like a box, but not a box, it's a circle instead and it goes into the mail but it's long and i have want to fly a painting to the usa and i don't know the word in french…(good god, what IS the french word for 'tube'?!?)
madame: une tube?
moi: bien sur, une tube.