Cento is a Latin word which means “patchwork.” The form goes back to the second century! The objective in a patchwork poem is to put together lines of poetry, each of which is borrowed from the work of a different poet. This is not easy since the entire poem must make sense! If you want a bigger challenge, you may make the task harder by using the rhyme scheme: aa, bb, cc. However, no matter what choice you make, the meaning, the tense, and the person must be consistent!
Example:
Those are pearls that were his eyes. [(a) Shakespeare]
And the wild wind sobs and sighs [(a) John Clare]
We all conceive the loss of what we love [(b) Robert Pack]
The frozen wind crept on above [(b) Percy B. Shelley]
It was almost easy to say goodby. [(c) Stephan Dunn]
Look at the stars! Look at the skies [(c) Gerard M. Hopkins]