Metatron is an angel described in Jewish and other Abrahamic religious texts, variously identified as the Scribe of God, the Lesser Tetragrammaton, et cetera. He/it is closely identified with the prophet Enoch, and by many accounts they are one and the same entity.
The cube itself consists of thirteen (doz. 11) circles, six of which emanate out from seven hexagonally packed circles in the center, with line segments connecting the center of each circle with the center of every other circle. This has the effect of producing a highly hexagonal pattern onto which one can map orthographic projections of all five Platonic solids. Note that this figure can also be expressed in the form of an actual cube, which sixteen (doz. 14) spheres instead of thirteen circles.
"In early Kabbalist scriptures, Metatron supposedly forms the cube from his soul. This cube can later be seen in Christian art, where it appears on his chest or floating behind him. Metatron's cube is also considered a holy glyph, and was often drawn around an object or person to ward off demons and satanic powers. This idea is also present in alchemy, in which the cube was favoured as a containment circle or creation circle."