The speaker looks back at themselves in a library, picturing a person as a book waiting to be bound, something unfinished and in need of putting together. That fits the title, "Some assembly required." But the neat, bookish image is quickly disturbed. The speaker admits they might "do a little coke," and the word "ice" suggests a desire that has hardened and gone cold rather than warmed into anything satisfying.
The middle lines turn inward. Light on a dark day brings clarity, and in that glare the speaker recognizes "what devil / is within me." It reads as an uneasy moment of self-knowledge, not a boast. The ending is quieter and sadder: the speaker's heart "vexed" them all night, apparently because they kept putting off "some small possible kindness." The mood is guilty and restless. The poem sets a wish to be whole and good against a habit of delay and temptation, and it leaves that tension unresolved.