JMorris @ THR asked for the plans. I wouldn't copy and share it with him b/c of copyright infringement but I did find an online link that I can share. 
https://forum.vintageairgunsgallery.com/girandoni-girardoni-type-airguns/girandoni-book-by-g-baker-and-c-currie/
Here is the THR link: http:// https://www.thehighroad.org/index.php?threads/why-arent-girandonis-widely-made.907710
https://forum.vintageairgunsgallery.com/girandoni-girardoni-type-airguns/girandoni-book-by-g-baker-and-c-currie/
Here is the THR link: http:// https://www.thehighroad.org/index.php?threads/why-arent-girandonis-widely-made.907710