As widely known among ardent fans, the Zoffy costume used in the final episode of Ultraman (while also worn by Satoshi Furuya) is said to have been the reused Type A suit of Ultraman with the newly made Type C Ultraman mask attached to it.
According to the information shown in a recent book, however, it is speculatively explained the Zoffy mask could have been one of the three masks Akira Sasaki made out of the original mold of the Type C Ultraman mask.
These three replica masks were made by Sasaki for his own possession and to gift Tohl Narita and Satoshi Furuya with the other two masks in commemoration.
The speculative explanation puts it as it might have been done right after the Type C Ultraman suit was completed and the replica mask Sasaki had could have possibly been used for the Zoffy costume.
It might be plausible given the Zoffy mask has no eye holes just like the masks possessed by Narita and Furuya.
After the shooting of the final episode, it is also speculatively explained the Zoffy costume was used as Ultraman at the attraction performance shows held around the nation after removing the rivets off the chest and the upper arms with the added lines repainted.
The photo borrowed from online and shown above is said to be the Ultraman costume possibly remodeled from the Zoffy suit used in the final episode of Ultraman with the details left unknown (the actor is apparently not Satoshi Furuya).