o poster tube, where art thou?

Every now and then I need to purchase a product that I'd guess to be quite commonplace but then turns out to be completely unheard of in Mexico. Last year I had this problem in Huajuapan when I set out to buy some resume-quality paper. Turns out there's no such thing. This weekend I've run into it again as I've tried to buy a mailing tube for some posters I want to mail to a friend. You'd figure that it would be a fairly easy product to find, but now having inquired at probably every papeleria here (at there must be at least 50 of them) I've learned that this is a technology that has not yet been unveiled here. People seem to understand me when I explain what I'm looking for - a tube made of cardboard that could be used to send a rolled-up poster through the mail - but as I describe the thing it becomes clear that this is the first time the concept has ever entered the shopkeeper's consciousness. But they do seem to respond in such a way that suggests that they'd approve of such a product if it ever were to be invented. So maybe one day I'll make my own, patent the design in Mexico, and make a fortune. In the meantime, it looks like my friend is going to get a big manila envelope with some folded-up posters inside.