A Matter-energy conversion matrix was a component of replicators and transporters in the 24th century.
Realigning this matrix can convert a replicator into a small transporter with the capability to transport a small object a short distance. Doing so, according to Odo, requires specialized training not commonly available.
Operatives of Klingon Intelligence, in 2371, did just that in order to transport a surveillance device with a high-energy laser into a panel on Deep Space 9. This device was discovered with the help of Miles O'Brien, who had been to a few hours in the future and witnessed himself killed by the device. Due to this intervention, that event did not occur. (DS9: "Visionary")