Chances are you've never heard of Carrozzeria Caprera but they designed one of the most beautiful cars based on the 850: The Caprera Berlinetta. Very little to be found on the internet so enjoy this photo:

Caprera 850 Berlinetta

In their enthousiasm, a Belvedere was built too, a Familiare based on the 850 Berlina. Finally you could take your weekend groceries with you in one go.
Caprera 850 Belvedere

Their largest business achievement was the construction of steel sliding roofs:
Caprera 850 Berlina Schuifdak

Not a lot of information can be found about these sliding roofs too so I am happy with some pictures from Quattroruote.