Going over the contents of the demolished apartment, I chanced upon a few puzzle mats that my niece and nephew used to enjoy playing with. There used to be 40 or so pieces when they were 3 and 2 years old. As always, I felt bad throwing them away: First because they are in good shape and second because they are made of rubber therefor non biodegradable. I couldn't use them as mats because there were only a few left. I played with them for a while until I decided to connect them into triangles.
Then I just place a plastic bag inside. I have loads of plastic bags hidden in storage that I have no idea what to use for. I guess you can make a square but my plastic bags can only fit in a triangle. I made 4 triangles for paper, plastic, cans and dust. I like sweeping the floor.