Place a heavy glass ramekin into a deep stockpot. Fill the ramekin 3/4 full with water to weigh it down. Place rose petals or herbs around the exterior of the ramekin in the bottom of the pot and cover with water halfway up the side of the ramekin. Place a shallow soup bowl on top of the ramekin. Bring the water and rose petals to a boil. Lower heat to simmer.
Place a stainless steel bowl on top of the stockpot. It should be large enough to seal the pot, but shallow enough so that its bottom is above the top level of the soup bowl. Fill the top bowl with ice.
Simmer the mixture 3 to 4 hours, depending on the amount. As the mixture boils, the heat rises and hits the cold bowl, causing it to condense and drip down into the inner bowl. Replace ice as needed as it melts.
When done, the small bowl will contain the rose water. It will have a layer of rose oil that is the essential oil or extract. Separate the oil from the water, you can use as you do other extracts.