Functional Ukulele (Playable)
Functional, playable, Lego ukulele! Meant to have ukulele strings on it, but Lego Ideas rules state there can be no non-Lego components, and Lego doesn't make ukulele strings--so provide your own after you build it and enjoy playing (the 4 parallel Spiderman web pieces in the last photo are just there to give you an idea of string spacing).
I believe this would be an awesome Lego set for children and adults alike. In adult hobbyists (ukulele-lovers and Lego-lovers alike) the appeal is obvious. In children the potential benefits are staggering. A project like this would foster a love of Lego, a love of engineering, and a love of music. It would be a perfect gift for parents to give their children to introduce them both to music and design. Tired of fighting your kids to practice an instrument? Get them emotionally invested in an instrument by having them build it first!
Also, consider that many elementary schools in the U.S. introduce the ukulele as one of the first instruments for kids to start learning. This project provides a practical application of Lego that serves as a natural bridge between an elementary school kid's love of Lego sets and the middle school/junior high elective tech classes (like robotics and engineering) that are based on using Lego Education sets like Lego Mindstorms. Foster a continuing interest in Lego at a time when most tweens/early teens switch exclusively to video games as their entertainment, and you not only keep a valuable segment of the population as buyers of Lego products, but you create lifelong Lego-lovers who will share Lego-building activities between the generations.
This ukulele is concert-sized (~ 22 7/8 inches / 58 cm). No glue, just held together by good old Lego power! And it sounds pretty good too once you put strings on it--watch this video to see how it sounds: