4

Here is a link to a page on the Jaycar website that shows the RGB 4x4x4 cube. Dimensions are not clear or obvious and maybe could be inferred from the size of the LEDs :
Following the link to the Downloads will bring you to this pdf. The construction instructions in the pdf might give a good guide to assembly but they do not detail any form of testing.

Here is a summary of the work I have done and appreciation that I have for the Freetronics Cube. The Cube provided a point of focus for many technical aspects of electronics and computing. By the way, I am letting Grammarly suggest changes to the spelling and grammar in this particular article.