This ‘instructable’ is on making a LED CUBE but the thing which matters is the size of it. It’s just half an inch in size and is built by using SMD’s LED’s that we often see in company manufactured boards. It’s a 3x3x3 based LED board and is controlled by an Arduino. However to make a cube this small, you will require an extraordinary skill to solder the components. Even the resistors used are SMD ones and the overall cube is built on a perfboard.
For a cube to be designed, the nodes for the 9 LEDs in each horizontal layer are tied together. The cathodes for 3 LEDs in each column are tied together. The Arduino code can turn on any one LED by knowing which of the 3 layers and which of the 9 columns the LED is on. Setting the corresponding layer HIGH and the column LOW turns on the LED. A beautiful project to work upon but you will a lot of practice and obviously a magnifier to solder the components. I would recommend to start by building a bigger cube comprising of normal leg based LED’s and then move into this.