In 2369, Reginald Barclay used a tech cube on the USS Enterprise-D to store the holoprogram Picard Delta One, trapping the rogue holograms James Moriarty and Countess Regina Barthalomew. It was latter coupled with an enhancement module to provide the program with enough active memory for a lifetime of experiences. (TNG: "Ship in a Bottle")
Background information Edit
While only referred to in dialogue as "the cube", the script for "Ship in a Bottle" used the term "tech cube".
The prop used to represent this device was designed by Makeup & Effects Laboratories. Prop fabrication supervisor Don Coleman later said of the prop, "It was machined up and silk-screened to get the pattern on the pieces before it was assembled. There was a light in the bottom so it would light up when you flipped a switch." (Star Trek: The Next Generation 365, p. 289)