One downfall to remember is that construction paper won't stick to itself and therefore cannot be covered. You can use felt as in constructions paper. I have a large sea-blue piece of felt for water and green for land. I can go on and on. The medium weight works best.
Directions are below.
In a hurry, I made a graphic on my computer and printed it out on the neat Barbie Fashion-Designer sheets. It is a sheet of fabric attached to a sheet of paper. Draw your own design, or find a picture of one you wish to make a flannelboard piece for. Place the pellon on your design and trace in pencil. Remove the design and place the pellon piece on a scrap paper.