I work in a place where we use a lot of vinyl for shirts and signs. This usually leaves us with a lot of 3" wide rolls of cardboard. The company is supposed to pick them up but they only do it when they want (which is hardly at all). So instead of tossing them, we've been giving them away to folks who need them for shipping purposes and to store posters in (especially usefully for teachers).

I've been using my scrap or leftover filament to make these. They don't take very long. Its up to you if you want to create supports or not. I usually don't to save time and filament, then I just trim the bad parts of it off (doesn't take long at all).

I know these are nothing new but seriously very useful when you want to safely store things inside the cardboard tubes. Don't need to tape the ends up or stuff paper in them to help. These should be snug, but I recommend printing one first to make sure.