We will ave the following:
First, we can see that the area of certain segments is the same [each face has an equal image], now we will have to determine the area of each one of those faces, eaxcept for the copies, that is:

Now, we will then have that the total surface are is given by:

So, now we simply replace and solve for AT, that is:


So, the total surface are is 338 mm^2.