I thought of this, each member here, if you had an unlimited budget, how exactly would you build your perfect mattress? Including theoretical densities like 7 pound memory foam if you could buy that on its own.
Unlimited budget means you can start your own mini mattress manufacturing facility. Get a mattress table, tape edge machine, sewing machine, pneumatic hog ring plier, etc.
Only two constraints: (a) don’t build those 15" to 20" thick mattresses (b) avoid too many layers.