A diemaker is a specialized job, and there are not many synonyms for it. You could use words like toolmaker, mold maker, or pattern maker when describing someone who creates custom tools or molds for manufacturing. Additionally, some machinists or metal workers may also have skills in diemaking. Another related occupation is a die cutter, which refers specifically to someone who cuts material using a pre-made die. While there are not many synonyms for the word diemaker, there are many related professions in this field that require similar skills and knowledge.