On a dry stainless steel or cast iron pan - NO NON-STICK PAN PLEASE! - spread out the rice in a single layer or close to a single layer and roast, stirring occasionally in the beginning and then frequently as they start to get opaque in color.
You'll know it's done when you see opaque rice grains and/or the color turns caramel color. Rice can burn very quickly so stir frequently and watch the pan carefully. Lift the pan from the heat if you have to. DON'T BURN THE RICE. It'll make the whole batch taste awful. Trust me.
When most of the rice is either opaque or browned, take the pan off the heat and add about 3 cups of filtered water and let the rice soak for about 2-3 hours. If you don't have time, 30 minutes soak will be ok too. You'll just have to blend longer. After soaking for about 3 hours, rice will be a bit softer. Pour the rice and water mixture and the rest of the water into a blender and blend well, starting at a low speed and gradually increasing to high speed. Blend for about a minute or two.
Stop the blender and stir the mixture well with a long spatula. Make sure to stir the rice that's settled at the bottom well.
After it's completely blended, strain the milk over strainer or fine cheesecloth. Add sweetener if you'd like. Personally, I don't like sweetened rice milk so I add a pinch of cinnamon to mine. It's delicious without the added calories. You can store in a glass carafe for about a week in the fridge. Stir or shake well before pouring.
What do you do with the strained rice? Add about ¼ of water and cook it. It makes a delicious Cream of Rice!