Whether making crafts, installing plumping, or starting a new construction product, you probably need 50mm pipe at some point. They come in metal, plastic, and vinyl versions so find the type appropriate for the project.
When shopping, keep in mind which connectors you need. For example, a 50mm pipe for water needs different connectors than a stainless steel pipe. A 50mm pipe is the only thing standing between you and the connections you need.