The text is a play on the phrase 'First Rule of...', typically used to introduce fundamental principles. However, it does not exploit different meanings of a word or similar-sounding words for a humorous or rhetorical effect. It seems to be a humorous take on the concept of tinkering, suggesting that one should keep all parts when working on a project, but it does not fit the definition of a pun.
First Rule of Intelligent Tinkering - Save all parts