In a perfect world everyone would be carrying a travel mug or thermos at all times, to help curb the waste generated by single-use coffee cups and their lids. Perhaps there is another way: a compact device that would reduce the need for plastic lids.
This reusable coffee cup lid is about the size of a hockey puck. It features a cap that is removed and fastened to the bottom of the coffee cup*, much like the cap from a marker pen. The lid features a flap that fastens open or closed.
The compact design makes this easier to pack around than a travel mug. Because the lid is sealed on the top and bottom when not in use, you don’t have to worry about washing this immediately after finishing a coffee. It can be washed or rinsed later.
I thought about including a third part, a ring that would act as a sleeve. That still could be an option but I want this to be as simple as possible.
*It doesn’t have to be fastened it to the cup, I just wanted that convenience so the coffee drinker doesn’t have to carry it around separately.
Dave's Geeky Ideas 