Twin-Point, Flat Back??
The word “flat” used in connection with the top or back of a mandolin (or guitar) is a bit misleading, as they are, in general, made with a slight arch; the arch being induced by the instrument’s internal structure. I imagine that back-in-the-day, they were referred to as flat, because they’re relatively flat compared to an arch top, but I guess saying “I’ve got a relatively flat top compared to an arch top mandolin,” is a bit too wordy!
In this video I concentrate on how I make my “flat” backs.