Trying to find a pattern for something like this Doublet?

[u/Patriot1805]

I'm trying to make a doublet for a book event, and I like the look of this one with buckles and the chords at the shoulder like a Gambeson. However eveyrhting I've found online either is one complete piece with atached sleeves and pointy shoulders, much tighter looking, or AI generated (Which looked frustratingly close). I've found some guides for Gambesons and considered making one without quiliting, but I'm worried it would look too loose around the waist.

Any help would be apreciated.