I find it interesting to learn how coin design ideas develop over time - some journeys are straightforward, some take a turn or two. Here's a story of how the 1926 American Independence Sesquicentennial Half Dollar developed into the 1948-63 Benjamin
Franklin half dollar.
John Ray Sinnock was the Chief Engraver of the US Mint at the time the 1926 American Independence Sesquicentennial commemorative coins (Gold Quarter Eagle and Silver Half Dollar) were developed and issued. Sinnock served as Chief Engraver from 1925 until his death in 1947.
Though originally credited as the designer of the American Independence Sesquicentennial Half Dollar, John Frederick Lewis was eventually properly credited - Sinnock handled the sculpting and engraving of the design. The coin features the US Liberty Bell on its reverse. It is a reasonably accurate depiction of the Bell, even including its famed crack!
1926 American Independence Sesquicentennial Half Dollar

In 1933, the US Mint struck a Benjamin Franklin medal that was designed/sculpted/engraved by Sinnock. The medal depicts a right-facing portrait of Franklin on its obverse and four allegorical figures on its reverse. The figures represent (left to right) Philosophy, Literature, Science and Patriotism.
1933 Benjamin Franklin Medal

Nellie Tayloe Ross, the Director of the Mint (1933-1953), was a fan of Sinnock's Franklin medal and also an admirer of Benjamin Franklin. When she decided to replace the Walking Liberty Half Dollar with a Benjamin Franklin Half Dollar, she tasked Sinnock with creating the designs. For the new designs, Sinnock tapped into his work on his 1933 Benjamin Franklin medal (obverse) and his sculpting/engraving efforts on the reverse of the 1926 American Independence Sesquicentennial Half Dollar.
Note: Sinnock died before work on the Franklin Half Dollar was completed, Gilroy Roberts stepped in completed the task and added the small eagle on the reverse.1948 Benjamin Franklin Half Dollar
(Image Credit: PCGS CoinFacts.)The Franklin half dollar blended Sinnock's work on the 1926 commemorative half dollar (Liberty Bell) and his work on the 1933 Benjamin Franklin medal (Franklin portrait). 20+ years separate the efforts, but the connections are very evident.