Before starting you need to collect power supply cases. How many you need depends on how many bands you want to cover times the number of stations you want to outfit with filters. Let people know you are looking for them and ask for “standard” power supplies. People that do computer support at your workplace or work in computer stores might be good for a few. Computer shops that do repair might save them for you. Your local dump or transfer station might let you take them out of discarded computers. We collected 75 power supplies in a few months. Generic white box computers almost always use standard power supplies. Mid size and larger tower computers are also likely standard. Small format or unusually shaped PCs are likely non-standard. Collect the cases and strip out the parts as you go. There are many useful parts such as capacitors, switches, coils, line filters, fans, and more that can be recovered in the process. You can cut a quantity of blank aluminum pieces to fill the opening left by the cooling fan. These will usually all be the same size. You don’t need to fill smaller openings. Typical supplies we found had two other openings that often worked fine for the two RF connectors.