Inventing free counterpoint
This little example in both free counterpoint and free thythm required adding a second part. I used tuned percussion and the decay of the notes allows more dissonant voicing than would be pleasant with sustained notes. Essentially the two parts each contribute alternately to a single line in the central part of the bar where the top line is holding for more than crotchet at a time:
Audio file with marimba and xylophone voicing
PDF of the score
Here is just the audio file of a second example where I made the supplied bass line a bassoon part and added a cor anglais line. This feels a bit unimaginative so I may return to this one in due course. Arguably the challenge arises in the four-time repeated C sharps in the supplied second part: starting four bars out of a mere 8.