The blueprint of the Seaview shown above was sent out to fans who wrote in to Twentieth Century Fox during the 1960s and provides a great insight as to how they invisioned the layout of the Seaview (pre-Flying Sub installation). Blueprint is courtesy of Classic Film & TV Cafe.
Shared below is a gallery showcasing an early blueprint design of the Seaview miniature which gave the planned miniature twelve windows in the observation nose (dated 27 October 1960). This five foot blueprint was for the 1961 Voyage to the Bottom of the Sea movie Seaview which eventually only had 8 windows on the observation deck. The movie Seaview was used in the first season of the 1964-68 television series and then adapted in the second season to incorporate the Flying Sub bay, plus allowing the re-design of the nose to have just four windows.