There's stuff piling up and I need to get back into online sales to clear it out. I have a large metal tripod to sell, and no box. What do you do with items that don't seem to fit inside standard packaging? Maybe go to a camera store for a box?

If you have a gordon food service by you they usually have bins of free boxes in front of the checkouts.

If it is a tripod, wouldn't something like a mail tube work?  The round poster size ones?  I work retail and seem to have an endless supply of boxes that we crush, maybe if you ask a manager of a store you frequently shop at when the get deliveries, they may let you pick up some boxes on those days.