The Chu-Gon Dar cube was a very special item, capable of transmogrification. It was made by Jedi MasterChu-Gon Dar thousands of years before the Clone Wars. This item was only compatible with objects with a special Force aura. These objects, after several volcanic eruptions, rose from the old Jedi Temples, and lay scattered on Mustafar.
Many "glowing" items could be looted from killed enemies all over Mustafar. Putting various combinations of these items into the cube produced new items such as Mustafarian furniture, buffs, weapons, armor and other useful items.
An entry in Sony Online Entertainment's Knowledge Base that was published shortly before the release of Trials of Obi-Wan to inform players about the new features called these items "The Cubes of Jen'ha Tar".