Spread moss out on a piece of wire mesh to a depth of 1 inch, using tweezers.
Cut a piece of cloth netting 1 inch longer than the wire mesh on all sides. Lay the netting over the moss.
Flip the wire mesh over and bend down the sides of the cloth netting. Stitch around the mesh with fishing line to secure the netting and hold the moss in place.
Place the wire mesh moss side up on the floor of the fountain. Make additional pieces as necessary to cover the fountain floor with a carpet of moss.
Fluff out additional pieces of moss and tie them to underwater fountain structures with fishing line. Use staples when attaching it to wooden structures.