When it comes to finding synonyms for the phrase "making top of head," there are quite a few options to choose from. Some possible synonyms include brainstorming, improvising, winging it, spontaneously creating, ad-libbing, spur-of-the-moment inventing, and quick thinking. All of these phrases involve generating ideas or solutions on the spot, without much prior planning or preparation. Whether you're trying to come up with a creative solution to a problem, or trying to improvise a speech or presentation, using one of these synonyms for "making top of head" can help you convey the idea of spontaneous, off-the-cuff thinking.