"Mallet Instruments (Orff Var.)" [mp3 removed]
I took out the speaking parts from the Carl Orff piece Wiegenlied bei Mondschein zu singen (Lullaby to be Sung by Moonlight), posted earlier. That left me with about 8-16 bars of music*, which I cut up and overdubbed, letting the differences in pitch and tempo among the fragments create some new melodies. Then, I wrote new music for marimba and xylophone in the same key and tempo (more or less) as the recorded bass-xylophone and marimbaphone parts and dubbed them in throughout the piece, so it's now a new tune, but retaining some of the mood of the original (and that great G-major/d-minor chord alternation throughout).
*depending on how you count--according to the CD liner notes the tempo was 6/8 so I kept that and set the tempo at 111 bpm. My "measures" marking off audio samples and MIDI on-off notes may bear only passing resemblance to the composer's staff--but it worked, I think. (Orff-o-philes--and others!--may hate it.)