Put on disposable gloves and a dust mask. Drape an old sheet around the work areas so that the floor is protected. Pour the allotted amounts of perlite, peat moss, fibermesh and Portland cement into a large plastic mixing bin. Combine the ingredients with sufficient water until the mixture approaches the consistency of cottage cheese and can hold its shape when formed into a ball. Add water slowly as it is easier to add water than it is to remove an excess.
Place the plastic bowl upside down on the sheet. Coat the outside of the plastic bowl with linseed oil so that the hypertufa can be removed easily later. Pack a 2-inch layer of hypertufa around the plastic bowl, so that the wall of the flower pot will be thick and sturdy. Pat it down firmly so that the mixture bonds to itself and doesn't crumble off.
Make sure to flatten what will be the bottom of the pot so that the finished product will be steady and not wobble when placed on the ground. Use the dowel to poke one to three drainage holes in the bottom of the pot. Smooth the sides down with a trowel and then cover the hypertufa container with plastic wrap and set aside in the shade for at least 5 days to allow the cement to cure.
When you remove the plastic wrap, turn the pot over and pull out the plastic bowl. Rinse off the hypertufa container several times over the next two weeks. This will allow any remaining lime from the cement to be flushed away.
Place your new hypertufa container in its chosen spot. Fill with soil and flowers, admire and enjoy.