My own (rough and ready) take on the class exercise. I did it first, cause I was curious to compare Nikita's method to mine. Biggest difference in approach was making AR into iM when flipped, along with keeping it all in one line (that t-Y join gave me some trouble - it was hard to avoid the Y turning into an X).
This is another one I did ages ago - but this course (oddly - it wasn't really the recommendation) has inspired me to focus more on using a particular typeface as a base to get a more coherent design. Pretty much all my ambigrams are very freeform, and I really like the more structured foundation in the examples.