Straight copper pipe, at least 30cm long. 15 or 22mm diameter central heating pipe works well. (A hardware store may lend you a piece for a minute just to try this out) A circular neodymium magnet ...

“PVC will follow iron pipe sizing (IPS) whereas CPVC will follow Copper Tube Sizing (CTS),” Smedley says. It really depends on the application. “They both are great but for their own ...