Assuming some skill with a soldering iron, you should spend about thirty minutes constructing the generator. Connect a 24-volt incandescent lamp in series with either positive or negative output lead. 2-conductor lead wires. 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.