When I find a blueprint to make a complicated item or weapon, I shouldn’t be able to create a high quality copy of the real thing.
Weapons should be most often crafted as poor quality, have randomly selected attributes (ammo clip size, rate of fire, reload speed?) random attachment slots and break easy.
Armor should have quality grades too.
Items like Code locks should have anywhere from 2 to 4 digits, boxes should hold random amounts and when cars and electronics are added, they should be faulty to prevent them from being over-powered.
This would prolong the end-game and add a bit more variety.