The following experimental poetry form combines line count, syllable count and rhyme in a form that has some choice regarding its application.
In the form there are:
Eight lines. The poet can choose the stanza structure for those lines.
Thirty syllables. There is no syllable count per line requirement. The poet can choose how many syllables are in each line under the thirty syllable restriction.
Three lines that rhyme. The poet can choose which three of the eight lines rhyme.
Here is an example poem written in the form:
What gave you that idea?
That thick lead wall,
that’s so tall?
That’s just there …
hold on, have to run to the hall.