The 50's

 1958 VJ-22 Sportsman aka Chubasco 1958 = 2pChwMAm; 85-100hp Continental O-200B pusher; span: 36'6" length: 24'0" load: 500# v: 125/80-100/45 range: 320 ceiling: 13,000'; ff: 12/22/58. Fabric-covered wood airframe. Manual gear retraction. POP: reported kits built by 1976: 750, with about 100 known to be flying 

Initially designed for his own enjoyment ( snorkeling, scuba diving, and flying, Volmer's VJ-22 became the first amphibious airplane made available by kit for home construction.

https://en.m.wikipedia.org/wiki/Volmer_VJ-22_Sportsman