This sentence appears in Lídia Jorge’s book, O Organista:
Um instrumento feito só para dois pés, dois braços, dois olhos, uma pauta?
It looks like the only verb in this sentence is a participio passado. How is it grammatically correct to use a participio passado alone like this? Why is it not “fez”?
Olá! In many languages, including Portuguese and English, we see all sorts of sentences that are meant to be interpreted within wider contexts, many without any verb forms at all (e.g. “Oh, really?”; “Good job!”; “Ah, the dramas of youth”). This is acceptable 
“Fez” would not be suitable at all, because it would suggest that the instrument did something, when the sentence is actually explaining how or what the instrument was made for → the instrument received the action, so to speak, it didn’t execute it.