PIXIO

One PIXIO block is a plastic cube 8 x 8 x 8 mm in size, weighing just over 1 gram, which has 6 magnets inside. The polarity of the magnets is designed in a way that the blocks can be connected to each other in any sequence from different sides.
Just take the PIXIO block in your hand and place it where you want it to be - BANG! - the PIXIO block is connected.