There are many synonyms for the phrase "slowly but steadily though." Some options include gradually, consistently, progressively, steadily, little by little, inch by inch, bit by bit, step by step, and slowly but surely. Each of these phrases conveys the idea that something is being accomplished slowly, steadily, and without interruption. They all suggest a slow but sustained progress towards a goal or desired objective. Depending on the context, some of these phrases may be more appropriate than others, but they all share a common theme of perseverance and the idea that success comes through consistent effort and patience.