This prelude is an interesting harmonization and modulation exercise. I wanted to modulate from F major to F# minor which is a very distant key to F major.
So I had to include a couple of intermediate keys: Bb minor (harmonic Subdominant of F major) and Db major (harmonic Dominant of F# minor changed enharmonically from C# major).
Then of course I had to go back to F major through these intermediate keys in the opposite direction.
Here is the full tonal plan:
Here is the PDF file for printing. Try to supply the missing middle parts yourself and avoid parallel fifths and octaves. I used only root position chords and chords in the first inversion. You can also add a little more dissonant four-note chords whenever you see a possibility.
After you are done, post your time to comments.