A drinking cup that can be dropped off after use at many different places so they can be returned to cafeterias for reuse.
Disposable drinking bottles and cups make up a large part of solid waste. In a place like a university, it should be possible for most people to get beverages from a small number of cafeterias or shops and return their drinking vessels to places where they can be easily collected tp be washed and reused. These cups would be made of a durable material and have a logo printed on them with instructions to return them for reuse. There would be a lot of containers around the campus with the same logo on them to make it easy to do.
This plan would at first involve cups for water and cold beverages but could eventually include hot beverage cups, plates, bowls, utensils and take-out boxes. The drop-off and return system could extend to the area around the university. Even if some kind of disposable top was used for the cups it would still generate less waste than now. People could be given some kind of discount on their next beverage or meal if they bring the items directly back to where they would be washed.