When it comes to antonyms for the word "sketch out," one might consider using words such as "fill in," "detail," or "elaborate." These antonyms connote a sense of depth, complexity, and detail, in contrast to the quick and rough outlines that are typically associated with sketching. Other antonyms might include words such as "erase," "delete," or "edit," which suggest a revision or removal of previously sketched ideas. Overall, the choice of antonyms for "sketch out" depends on the context and the desired level of detail, precision, and clarity in the final product.