The phrase "throw together" suggests a rushed and haphazard approach to preparing something. Antonyms for this term might include words like "meticulous," "deliberate," or "careful." A person who takes a meticulous approach to cooking might be more likely to follow a recipe carefully and measure out ingredients precisely, while someone who throws together a meal might improvise and use whatever ingredients happen to be on hand. Similarly, a person who takes a deliberate approach to designing a space might carefully consider every detail, while someone who throws together a room might simply place a few pieces of furniture haphazardly. Ultimately, the opposite of throwing something together is taking the time and care to plan and execute it properly.