The mirror cube/bump cube/mirror blocks is basically a 3x3x3 but one has to solve using the unique shape of each block instead of color. This makes the cube harder to solve, and trial and error are sometimes needed. The pieces range from small to large so no two pieces can fit in the same place. This cube is solved when each side is flat.
This cube mainly comes in two colors: silver and gold. There are other colors such as red, blue and black (they can be found on various sites such as Amazon, Mefferts, HK Now etc.), but only silver and gold are available from multiple manufacturers.
Many patterns that work on a regular Rubik's Cube work great on a Mirror Cube.
The 2x2x2 and the 3x3x3 Mirror Cubes are the only two in this family that have been mass-produced; others have been printed in 3D before (including bandaged puzzles, the Skewb, the Windmill Cube, and some cuboids) but were never mass-produced.
One variation (produced only as a sticker mod and is not mass-produced) is the Horror Cube; this has the standard colours of a regular 3x3x3, but applied to the Mirror Cube when in a scrambled state. The Horror Cube thus has two distinct "solved" states; one is a regular cube but with jumbled faces, the other is a lumpy shape with the faces each one colour but not a flat surface. These stickers are available from Olivérs, in two versions; a standard version (pre-determined colour solution) and a custom version (you specify what colour solution you want).