The major physical build differences are weight, top braces and string height off of the top. Build as light as you can; the flamenco guitar is the snare drum of the guitar world. Some builders use spaced, varying sized, tentallones on the top rather than continuous kerfing. (Think small, large, small, large with an appreciable space between each one to save weight and "free up the top." Scale lengths vary beween 650, 655 and even 660 in some of the experienced Spanish builders.
Bridge height is usually about 7 to 8 mm to the top of the saddle slot; in contrast to 10 - 12mm for a classical. This allows the saddle to keep a bit of height for adjustment and still keep the strings about 10 - 12 mm off of the top.
Neck width at the nut can be as wide as 54 mm. in lieu of the std. 52 due to the fact that many players like a bit more room between the strings. The first string is usually at least 3 mm from the edge of the fingerboard to allow for the pull-offs that are std. flamenco technique amongst the more experienced players.
Top thickness can vary appreciably from piece to piece... as we all well know.... but the primary objective should be to minimize sustain with as light a top and bracing style as possible while still maintaining good bass and treble response. A difficult objective but that's what separates the men from the boys in the flamenco world. The professional players disdain any appreciable sustain because of the rapid picado runs and machine-gun tempo of many of the pieces.
A bit of string buzz is acceptable as a trade-off for low string action. The golpes (taps on the top using the 3rd or 4th finger of the right hand) are more easily accomplished when the action is low and the strings are close to the top of the guitar.
If you are building for authenticity then use Spanish Cypress and a Spanish Cedar neck. Watch a few of the Sabicas, Tomatito, Paco deLucia pieces on YouTube to get a feel for what I've tried to explain.
Good luck with your build. YMMV
_________________ Peter
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