The chains that Marley wear symbolize all the mistakes that Marley made when he was alive. Built from the same mold as Scrooge, he was a miser and is warning Scrooge that if Scrooge doesn't change he will carry around these same chains but longer because Scrooge has lived longer than Marley. These chains are like the sins you have in your conscience. It is a burden.
Marley says "I wear the chain I forged in life. I made link by link, and yard by yard; I girded it on my own free will, and of my own free will I wore it. Is its pattern strange to you?"
Marley anguishes his mistakes and doesn't like the chains, he has learned to live with his mistakes and knows he can't change them.
To make a long story short, the chains symbolize mistakes and are a warning to Scrooge to change so he can escape the fate of Marley's.
Marleys chain is made from steel purses, ledgers, cashboxes, keys, and his office materials.
It was forged by aspects of his life
Jacob Marley
Marley was wrapped about his bodies in a chain he forged in life. It was decked out with iron keys, ledgers safes and cash boxes . These represented his life's focus on making money and ignoring the plight of mankind around him
Marley's ghost in "A Christmas Carol" is often described as a heavy chain-clad specter, akin to a burdened, dragging anchor of guilt and remorse.
Jacob Marley's chains were made of cash-boxes, keys, padlocks, ledgers, deeds, and heavy purses wrought in steel. These items symbolize his earthly attachments and sins that weigh him down in the afterlife, as depicted in Charles Dickens' novel "A Christmas Carol."
In Charles Dickens' A Christmas Carol, Jacob Marley says that his chains are "forged out of life," meaning that all of the bad things that he did in his life came back to haunt him and are symbolized in the form of the chains.
These symbolised what was important to Marleys' in life. In his interaction with Scrooge he states that his business should have been "people".
It symbolises his sins; he himself forged each of fragment with every bad decision he had taken.
A chain made up of cash-boxes, keys, padlocks, ledgers, deeds, and heavy purses wrought in steel.
The interpretation depends on the sort of chain involved. A delicate gold chain might symbolize love and a binding commitment, whereas heavy iron chains symbolize slavery and bondage.
The first is used to descrive Marley "He was dead, as dead as a door nail" and the houses opposite were mere phantoms