Metatron's Cube is usually presented as thirteen circles and the lines that connect the middles of those. When you look at this image, the eye is first presented with hexagons and hexagrams; then with triangles and rectangles.
Note that the figure depicts the "six directions in space" (3 dark lines), and is essentially an expansion (by adding six circles) of the Star of David, located at the center. Note especially that the Star of David consists of seven points, although the center point is seldom emphasized. The Cube is a depiction of 12 around 1 like the disciples or the 12 tribes, the labors of Hercules and the zodiac signs.
The Cube is easier to see if we fill in six more circles. Note that adding the Pythagorean "Y" to the hexagon yields three rhombus, which is how we depict a 3D cube in two dimensional drawings. Studying this cube is a lesson in perspective drawing.
Overlapping the circles (so that the center of one is on the circumference of another) and making them opaque, yields this figure; the cube of three, composed of 27 spheres, 8 of which (2 cubed) are hidden, leaving 19 visible. This means that the cube of two is hidden with in the cube of three, just as the cube of 1 is hidden in the cube of 2. The cube of 4 conceals the cube of three.
Making the spheres transpart yields the figure known as "the flower of life", composed of vesicas. Note how you can see the "hidden" spheres, and how the center circle represents three different spheres; one at the front corner, one at the opposite corner and one in the middle of the cube.