Many readers will remember a Tom Hanks movie from 1988 called "Big".
In the movie a young boy gets supernaturally transformed into a twenty-something man and finds out what it's like to be big.
Perhaps the most iconic scene of the movie has two of the characters dancing on a scaled up "Big Piano"- that's the scene everybody seems to remember.
They turned the movie into a Broadway musical and later licensed the show to be performed in community theatre. My local community theatre (South Valley Civic Theatre
in Morgan Hill, California) decided to do "Big the Musical" as a teen show, and the production staff approached us to build a Big Piano that could hold its own next to the movie version and give our show a "wow" moment.
Not many people need to build a Big Piano, and if you do it's likely you'll have specific goals and constraints different from the ones we faced. This instructable is less of a detailed plan and more of a set of notes explaining the problems we were trying to solve and the way we chose to solve them. I hope other Big Piano builders can learn from our experience.