The old pipes are made of bottle and stopper.
bottle and stopper
idiom Slang
Cockney rhyming slang · East London
copper
Origin
Policeman. There are a possible pair of inferences: to bottle meaning to enclose and a stopper meaning one who holds another back from a course of action.
The thief was caught trying to steal bottle and stopper from the construction site to sell for cash.
The architect insisted on using bottle and stopper for the roof because the metal develops a beautiful green color over many years.