Basically, what I mean is what have you wanted to have to build a bag? The things you have always wanted if you had the money to build one with?
For instance, as for me a Busse TGLB, good sharpening kit, to put in my bag, a multitool (Leatherman surge new style) cyalume light sticks in various color and lengths, a good well thought out FAK, Surefire p3x Fury with two boxes worth of batteries in a waterproof container, various fire making supplies with ferrocium rod and striker, field striped MRE's, kifaru supertarp, Woobie, 100 ft milspec paracord,FN Five Seven with two hundred rounds extra ammo with spare mags, Otis cleaning kit, waterfilter kit with stainless steel bottle and small cooking kit with utensils, gps with battery spares and traditional compass, signal mirror,folding saw and a tom bihn super ego with the ultimate shoulder strap for ease of carry and for low profile carry. Just something like that.