I keep my puppet stage in a plastic grocery bag, when it is not in use.
Along the top of a bookcase I attached 3M "Quick Clips" with adhesive strips. I sewed a narrow hem on one selvage of two yards of sky colored cloth. The extra bulk helps the cloth hold in the clips.
The "sky" hangs behind a short bookcase. You could use a table on its side, instead of a bookcase.
For the ground I have green for "grass" or light brown for "sand." I sewed these two length of fabric together with a third piece of fabric inserted between as wide as my bookcase's top. This allowed both the green and the tan to reach the floor and cover the bookcase. With something narrow like a table, the middle insert would not be needed.
Here are some penguins on the "sand."
With a quick change, the "sand" can be turned into "grass" for a different puppet play. When you are done, just fold the puppet stage and store away until you need it again.