"The Dance" by William Carlos Williams is written in rhythmic verse which would mimic the rhythm of the dancing described in its twelve lines.
Imagery in the poem includes auditory imagery (what you can "hear") with words like "squeal" and "blare" and "tweedle," all of which describe the sound of the bagpipes which create the music for the dance depicted in the picture Williams is writing about: "The Kermess" or "Peasant Dance."
The metaphor is: "tipping their bellies (round as the thick-/sided glasses whose wash they impound)" which compares the dancers' bellies to the thick glasses that hold their drinks ("wash"). (This is a metaphor in the general sense, but specifically a simile, in that the author uses "as" in the comparison.)
There is no rhyme in this poem.
The structure of the poem uses several devices to support the images of the painting. Williams uses parentheses to add a visual aspects to support the poem's images of "roundness," as with "round" glasses and the dancers go "round."
The structure of the poem also mimics the dancers' speed as Williams' descriptions move swiftly along. For instance, there are no capital letters used at the beginning of the lines to slow down or give pause to the descriptions of the dancers swirling and pitching about.
Williams is able to use the concrete (words) to describe the abstract (the description of a painting), as well as embedding a sense of movement throughout the lines of the poem.