I want to make a custom Lego cat for my boyfriend, but have NO CLUE where to start

A dedicated LEGO fan is seeking community advice on how to heavily modify a retail LEGO set to create a custom replica of her boyfriend's cat. Since she is new to the hobby and lacks prior building experience, she is exploring several creative approaches to achieve this thoughtful, personalized gift.

Her primary plan involves purchasing the existing LEGO Tuxedo Cat set and swapping out specific pieces to match her boyfriend's cat's unique markings. To do this, she is considering either reverse-engineering the build booklet to order alternate pieces directly through LEGO's Pick a Brick service, or simply buying the set, figuring out which color changes are needed, and ordering replacement parts accordingly. As a more drastic backup plan, she even wonders if painting the completed LEGO pieces is a viable option, alongside designing a custom instruction booklet for the final creation.

While painting LEGO bricks is generally discouraged by experienced builders because it can damage the plastic and wear off easily, utilizing the Pick a Brick service or ordering specific replacement parts in different colors remains a very popular and effective method for custom MOCs (My Own Creation). For anyone diving into a custom color-swap project like this, it helps to stay organized by sorting your elements carefully, perhaps using a LEGO storage organizer to keep track of the different colored bricks.