The short version:
The materials the endearments require include index cards and time.
Each endearment is made in several steps. One is about discerning a set of finite possibilities of the word; one is about the organization of information, including the puzzle of superbinary choices. The final step is about the decisions, the intuitions, the what-all else by which a poem is made.
The longer version:
Start with a word. Make an anagram: a new set of words, using only and all the letters in the original word or phrase, repeating none. (To aid in this, I often note the number of letters in the word at the top of the index card.) The task involves some mental movement—rotation, you could say. Rearranging the words is easy, but seeing what letters are left is harder.
Make anagrams until you can think of no more combinations of real words using that set of letters. Take some time—new anagrams may appear slowly. Once you have the entire list, check questionable words in a good dictionary. (I use the Webster’s Collegiate I got at high school graduation.)
After eliminating nonwords, pattern out the resulting list roughly by parts of speech. Note anagrams that share a word with each other; among these anagrams, choose one. Sometimes the choices are byzantine and must be mapped out. Sometimes a choice creates a particular constraint: for my dearest dear, for instance, I chose between I and an, between a and and. Once repetitions are removed, use the remaining words to make the poem.
Each step takes a different kind of attention. Making the lists of words requires a kind of secretarial rigor. Making the poem itself requires listening for phrases and for sounds, telling stories, time, luck—the things most poems need. Making anagrams, as befits a middle step, falls somewhere in between the two. Sometimes, incidentally, it makes little tadpoles of poems.