Location (original): data0.dat/Assets/tpp/motherbase/script
EquipDevelopFlowSetting.lua is a major script used to control the flow of item and weapon development. It controls the GMP, resources, time, and levels required to develop items.
The script has been minified, but I have discovered most of the minified variables meanings:
It is possible to develop online items offline by setting p72 to 0, but upon reconnecting to MGSV's servers, they will return to their online state and will not remain developed if they were developed offline.