At the moment I'm working on my scorebook with etudes - I'm sure you've already noticed that much.
Here is a short piece that lasts as long as it took me to swim 100m freestyle in 1978, which was quite good at that time but is just laughed at today ^^
It sounds on the beautiful sample set of the organ "Saint-Jean-de-Luz",in the parish church Saint-Jean-Baptiste.
The nice thing about that organ is that you can octave all the pipes, so that the upper voice is very nicely set off from the accompanying voice.
Have fun with that short piece!