The Jedi Master Chu-Gon Dar created this item to create special Force sensitive items out of other Force sensitive items.
Over 3,000 years later, the Cube was discovered by the archeologist Ithes Olok. An unnamed spacer assisted Ithes in finding some ancient Jedi tablets. Ithes gave one of these cubes to them. The fate of the cubes is unknown.
It is unknown if there was just one or many of the cubes.
The cube has the ability to transform three special items into a single powerful item. It can only transform special Force sensitive items from the planet Mustafar. The items include powerful weapons (including a Lava cannon and others), mystic items (special Lightsaber crystals), and even art (like paintings).
Despite its power, the cube is no larger then a normal Jedi Holocron.
Star Wars Galaxies (first appearance)