When my son was in middle school, they had a project to “create” something useful, using a 2 liter plastic soda bottle. I think he ended up making a garbage bag dispenser, which would hold a roll of trash bags and had a slit through which you would pull one out.
This fellow did something similar = toilet paper holder, paper towel holder, plastic cup holder. Even a toothbrush holder. Darn, this guy has an imagination :-)
In a Home Power article, a 2l container was used as the cover for a small motor turned into a wind-power generator.