On the left is the one I made first, designed on the fly as I built it. The one on the right has a few modifications based on what I thought of the first one.
We have Skylanders in the house, so I asked my son to "Please put Perler Perry the Platypus on the Portal of Power".
These were designed as I built them, knowing the basic shape I wanted and having some experience building cubes. So there is no template, other than the finished product itself.