Imitation is a wonderful tool for an artist. It's why you see young, and even not-so-young artists in the Uffizi or the Louvre, copying old masters, striving to understand what they did, how they got certain effects, what the young or not-so-young copyist can learn from the experience.

One of the most painfully powerful movie scenes occurs in Amadeus, when the dying Mozart, unable to pick up a pen, asks Salieri to transcribe a piece of music for him. F. Murray Abraham, as Salieri, captures the pain and rapture of the mediocre composer writing down the notes of genius that he would never be able to create on his own, but are now taking form under his hand, in his penmanship. The moment is complicated by the facts that (a) Mozart is dying because Salieri has murdered him, and (b) he plans to steal the piece of music and pass it off as his own. But these monstrous facts are subsumed, in that moment, to the glory of creativity that is and is not his.

I don't recommend trying this at home, not that the occasion would ever be likely to arise.

But there are other things I would recommend not trying at home. I often used to give assignments that involved one sort or another of imitation, of a poet or a poem. I would frequently assign taking one line from Allen Ginsberg's "Howl" and writing your own poem around it. Or the old chestnut that everyone has taken a crack at -- write your own version of William Carlos Williams's "This is just to say." But there are others....

For example, W. B. Yeats’s “The Lake Isle of Innisfree.”

THE LAKE ISLE OF INNISFREE
  By William Butler Yeats

I will arise and go now, and go to Innisfree,
And a small cabin build there, of clay and wattles made;
Nine bean-rows will I have there, a hive for the honey-bee,
And live alone in the bee-loud glade.

And I shall have some peace there, for peace comes dropping slow,
Dropping from the veils of the morning to where the cricket sings;
There midnight’s all a glimmer, and noon a purple glow,
And evening full of the linnet’s wings.

I will arise and go now, for always night and day
I hear lake water lapping with low sounds by the shore;
While I stand on the roadway, or on the pavements grey,
I hear it in the deep heart’s core.

OK, I'm going to talk poet talk for a while, so if your eyes glaze over, I'll understand.  If you don't want to read it all, that's OK. Just read the  poems, because they're just about as good as it gets. 

For the purposes of scansion, I’ll put the stressed syllables in all caps, the unstressed in all lower case.

I will  / aRISE and /  GO now, /   and GO  ‘  to INN /  isFREE,

AND a  /  small CABin  /  BUILD there,  / of CLAY  / and WAT / tles MADE;

NINE BEAN- /  rows WILL  i /   HAVE there, /  a HIVE /   for the HON /  ey-BEE,

And LIVE /  aLONE /   in the BEE / -LOUD GLADE.

Three hexameter lines, followed by a tetrameter line. But what hexameter lines! Here's how I would scan them. The first line sets a pattern. A trochaic foot, followed by an amphibrach, followed by another trochee. At that point there's a caesura, and then the pattern changes. We have three iambic feet to end the line.

Second line follows the same pattern.

Third line there's a variation. It starts with an iambic substitution...or does it? "Bean" has to be stressed, but "nine" is almost as important, and the pattern of stress on the first syllable of the line has been established, so maybe it's pyrrhic foot. And the strictly regular iamb-iamb-iamb that finished off the first two lines is varied. There's an extra unstressed syllable, which doesn't seem strange, because we're used to the lilt of those amphibrachs in the first half of each line. So this could be another amphibrach -- a HIVE for -- but there's a breath pause after "hive," isn't there? Not a full caesura, but a breath pause. So the substitution is an anapest for the second iamb.

The fourth line is shortened to tetrameter, mostly regular iambic, after all the subtle and supple gymnaastics of the first three lines...except where it isn't. Another anapestic substitution in the third foot, and the fourth foot, though it can be read as an iamb, can also just as easily be called a pyrrhic foot, with two equally stressed syllables following the stress at the end of the previous iamb.

As Yeats says in another poem.

A line may take us hours maybe,
Yet if it does not seem a moment's thought
Our stitching and unstitching has been naught.

What makes this poem so magical is that it doesn't seem complicated at all. You can read it a hundred times, and fall in love with it every one of those hundred times, and never notice that it's metrically complex.

And you can also disagree with my scansion. An essay by Marit MacArthur and Lee Miller points out that 

One student might argue that Yeats’s speaker is resolute, determined to escape some unnamed unsatisfactory locale; “I WILL aRISE and GO[,]” he declares iambically! On this interpretation, the metrical expectation of iambs, in the opening line, would coincide with the emphatic rhythm, reinforcing the speaker’s ardent wish.