What's the DIY project that took way longer than you expected but was worth it

[MegaMike16]

Built a genuinely simple looking bookshelf that ended up taking three full weekends once I factored in mistakes, sanding, and actually finishing it properly, and I'm still proud of it years later

Curious what people's version of this is, the project that blew through your original time estimate completely but that you'd genuinely do again regardless

[RusticDaemon]

Refinished an old dresser I thought would take a weekend, ended up taking a full month once I discovered layers of old paint underneath, completely worth it in the end