A machine that turns thoughts into things. 
The Miracle Machine was a machine that could transform thought into reality through power of will.
History
The Miracle Machine entered recorded history in 2960, when it was given to the Legion of Super-Heroes in thanks for their stopping a rogue Controller. An advancement of the willpower technology created by the Guardians, the Miracle Machine can turn thoughts into reality, but it was regarded as dangerous, since if anyone in its presence wished for an instant—for example, to die—that wish would be granted. The Miracle Machine was used on a few separate occasions, but was ultimately locked in a block of Inertron in the Legion's vault.
During the Final Crisis, Superman was pulled forward in time by the Legion to help them stop Superboy-Prime, who had assembled all the various opponents of the Legion for a final, apocalyptic battle. However, what the Legion had not expected was that Darkseid would make his move to conquer Earth, warping space and time around him and preventing the Legion from returning Superman to his time until after the Anti-Life Equation was released. To repair the damage to reality, Brainiac 5 had Superman look at the Miracle Machine and memorize its schematics.
Trivia
- The Miracle Machine has some connection to Metron, one of the superbeings of the Fourth World, since the design on the front of the device resembles his facial markings.
- Darkseid called the Miracle Machine a cargo cult Mother Box[1], implying that it was created in the image of the technology that underpins Mother Boxes, but not with an understanding of its actual workings.