The Third Prototype Boba Fett costume is often referred to as the Preproduction #3 costume, prepo 3 costume, or simply PP3 costume.

This costume was supposedly painted by Joe Johnston and bears a striking resemblance to the final costume seen in the Empire Strikes Back.

This costume was the least photographed, with only a few images being printed in Star Wars Chronicles and The Making of Star Wars: The Empire Strikes Back.
The helmet from this costume was painted virtually identical to the final helmet seen in the Empire Strikes Back. This helmet was 3D scanned in 2005 during the creation of Master Replica’s 1:1 Boba Fett helmet replica.