Fundamental group of 1-skeleton of cubes

How do you compute the Fundamental group of the 1-skeleton of the 3-cube $\displaystyle I^{3}$ = $\displaystyle [0,1]^{3}$ ? What about the Fundamental group of the 1- skeleton of the 4-cube $\displaystyle I^{4}$ ?

I know the Fundamental group of a space X at a point $\displaystyle x_{0}$ is the set of homotopy classes of loops of X based at $\displaystyle x_{0}$ . And that the 1-skeleton of a space X is the union of all cells of the CW complex for X up to dimension 1. But how do you find the fundamental group of the 1 skeleton for those cubes?