One of the simplest processes using matter replication is the duplication of an existing object. In fact, duplication machines are far more common in most settings than full-fledged replicators because they don't require the storage of massive amounts of blueprints.
Replacing the databank of blueprints are advanced sensors that analyze the construction of an object and transform the collected data into a blueprint of the object. Once the scanning process is complete, the replicator produces a copy of the desired object just as quickly as creating it from a stored blueprint. The duplication machine does not store blueprints, and so each object must be scanned before duplication can occur.