I used to be annoyed by all the plastic containers - apples, eggs, tomatoes, nectarines, mangoes - everything seemed to be packaged in wasteful plastic.
Then I noticed they looked like mini-greenhouses.
Not only were they available in multiple sizes, they were easy to stack until the first seeds sprouted, and I could water them easily without them dripping all over my window sill.
I can use a sharpie to identify individual cells so I can plant multiple varieties of tomatoes in one flat. I could also note the date that each container was planted.
As the seeds sprout and grow too tall for their ceilings, it will be easy to cut off the top of the carton, and keep them under a grow light until I'm ready to plant them in the garden.
In the meantime, my windowsill is full in an effort to keep me from going crazy when we have snow on the ground.