S.H.I.E.L.D.s Life Model Decoys are one of its most genius inventions, so its fitting that their original creator is one of the most famous inventors ever. LMDs have, in fact, always been a part of S.H.I.E.L.D., but not the S.H.I.E.L.D. that most readers are familiar with. Their real origin lies hundreds of years in the past. However, in the Marvel Universe, nothing is ever forgotten forever, and one fateful mission brought them into the modern age.

https://screenrant.com/shield-lmd-robot-technology-leonardo-da-vinci-invention/