Francis Lombardi between 1947 and 1973 designed several models based on Fiat's. The most famous is probably the Grand Prix, but the Lucciola's (4-door versions of 600 and 850) wee also built in small numbers. Here I collected a few things about the Fiat 850 Lucciola.

Lombardi 850 berlina 4drs

Lombardi Lucciola 850 4drs

Lombardi 850 4porte

He also had an idea for a 2-door, the "Smart", based on the Fiat 850 Special:
Lombardi 850 Smart

Once again: images from Quattroruote!