Insulation is shrunk over soldered connections using a heat gun or hair dryer. Fourteen gauge is the preferred thickness. Pure silver is sometimes available at electroplating supply companies. Or, inquire at a jewelry store specializing in silver about who their wholesale supplier is. If the silver colloid is to be ingested or injected, be sure to use distilled water.
Tap water is fine for other uses, such as for a topical spray or for plants.
Also, before beginning to make your colloidal silver you will need to make a saline solution for enhancing conductivity. If you are using filtered spring water, no saline solution will be needed as spring water already has a natural saline content. Saline solution can be made by mixing approximately four ounces of distilled water with a teaspoon of sea salt in a separate container. Do not use common table salt as table salt has chemical additives. After stirring the salt solution for a minute, pour some of the water into an eye dropper bottle.