The Build Your Music robotic xylophone is designed around the Trophy 25-note (2-octave) bell set.  I chose this one because it met my criteria of being reasonbly priced (under $100), and yet had a good enough sound that I could feel satisfied when listening to it.

The Trophy Bell Set is available in multiple configurations:

Any of these Trophy Bell Sets can be used.  I prefer using one of the 2-octave 25-note models, because with both the white and black notes, it is possible to play songs with both the melody and harmony.  Also, 2 octaves is a wide enough range that most songs are recognizable when played.  The instructions on this web-site are shown using the G-to-G Model Tr9012, which is also pictured below.  As of this writing, this instrument can be purchased from guitarcenter.com for $60.

Trophy 25-note Chromatic Bell Set, Model Tr9012



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