This week's form is less about rhyme schemes, counting syllables, and refrains. In fact, ars poetica has nothing to do with structure. Rather, it's focused on the content of the poem, because ars poetica is the art of writing poetry about writing poetry.
In college literature courses, we'd occasionally discuss meta-fictional interpretations of text. Ars poetica is kind of like that, except it's right out there.
Frank O'Hara's "Why I Am Not a Painter" is a great example of this form as is Emily Dickinson's "Tell all the truth but tell it slant." As you'll notice, the structure of both poems is different, but the content is focused on writing poetry.
Play with poetic forms!
Poetic forms are fun poetic games, and this digital guide collects more than 100 poetic forms, including more established poetic forms (like sestinas and sonnets) and newer invented forms (like golden shovels and fibs).
Here is an example of Ars Poetica:
A Stoic Pear, by Robert Lee Brewer
a stoic pear wouldn’t dare
pare down what it means
to be a pear or compare
itself to other pears
a stoic pear doesn’t stare
into the depths of its own pear-ness
or declare some pears
better than all other pears
there’s no flair to its existence
a stoic pear’s only there
nothing more than a pear
(Note: "A Stoic Pear" is an anagram of ars poetica, so it's a slightly less obvious piece of ars poetica but ars poetica nonetheless.)