Here's a list of things that need to be done for the project:

• Add build instructions.
• Develop the software and put it on Github.
• Make the device's fabrication easy: make it out of cardboard.
• Choose the sensors (piezo).
• Design the sensors interface circuit, and make it.
• Design the graphical user interface.
• List of features (non exhaustive): 
  • Visualize and scroll notes in real-time (rhythm games style).
  • Progressive training mode which adapts itself to the player's level.
  • Import and export music sheets.
  • Possibility to manually change the tempo, and add a click sound.
  • Training mode that evaluates and rate the user's skills: jitter, velocity, etc.
  • Manage chords, and complex melodies.
  • Save playing stats, and show progression, parts to improve, etc.
  • Advanced training exercises to improve specific skills: velocity, rhythm, etc.
  • Rating system that is saved every time you play.
  • Complete stats logs.
  • Compatible with all the eXa software suite to allow music composition.
  • Probably some other things to add...