Sometimes other people ask me to bring their ideas to life. I usually say, make it yourself, but some ideas are too fun to resist.
The local escape room wanted a playable toy piano that audibly plays the notes pressed and when the keys are played in a specific sequence, a special audio file is played.
I made the piano from MDF, working to a drawing that was provided. I made up the key press mechanism, which is just a series of wooden keys resting on springs, just above limit switches. The switches are wired to an Arduino that's connected to a DFMini mp3 decoder and a 3W speaker. The wiring and code are pretty straightforward, but it's robust and works consistently. And everyone knows it's that last 1% that's the hardest to achieve and the part you're most proud of.