The antonyms for the phrase "smashing to smithereens" would be preserving, protecting, and safeguarding. Instead of breaking and destroying, these antonyms imply taking care, maintaining, and ensuring something remains intact. Synonyms for these antonyms could be conserving, securing, and sheltering. Additionally, some words that represent the opposite sentiment of "smashing to smithereens" would be constructing, building, and creating. Rather than reducing something to tiny fragments, these antonyms suggest putting together elements to form something new and whole.