Cut out an opening on one side of the paper bowl. This will be the cave entrance.
Dampen the plaster sheets lightly in a bowl
Spread them over the paper bowl to mimic the shape of a cave. Make sure to leave the entrance uncovered. You can put some crunched up paper or napkins at the top of the bowl to make the top more rounded.
Let the plaster dry.
Paint the cave grey
Brush a thin layer of glue over the entire plywood base
Sprinkle turf grass powder over the glue. Use 2-3 colors to create a realistic shaded scene.
Let rest a few minutes, then shake off excess powder.
Glue the cave to the back center of the base.
Glue trees, bushes and rocks around the cave as desired.