Week a sustainable city should encourage people not wasting resources and recycle more. Some projects like this basketball court sticker placed around garbage cans to make throwing out litter a game can encourage people to recycle in every day life
TREE HOUSE Even if u weren't handy w/wood working tools u could use craft store woodburning plaques or even wooden cutting boards (many have holes in them) or get wood scraps from a hardware/lumber store
Campers create a tower of tree cookies in the Natural Play Area's messy materials zone. This zone encourages kids to interact with nature on a "messy level" through stacking tree cookies, playing in the sand, and more.