I found a 175 blueprint (acsendant) that was wicked awesome, but it cost 4000 metal ingots, 10000 element dust, 500 oil, 2500 crystal, and 3000 polymer. Am currently farming resources for it, afraid I may never make it.
For a basic enforcer, go around the city and gather at least 500 element dust from lampposts(preferably more), kill a few isolated enforcers until you get 20 oil, go to the wasteland killing the weaker corrupted creatures for corrupted nodules (they can be used as polymer)
When you collect all the resources, go to a city terminal and craft your own enforcer.
The Enforcer drops a blueprint upon being killed and the blueprint dropped will give you that exact enforcer you just deafeated. It will have the same color(s) and stats as the one you killed and can be crafted at any city terminal. The higher the stats the more ingredients you will need.
In extinction, you can kill some of the defense units, then if you go into the badlands you find this small thing that allows you to build one, if you have enough resources, the more leveled up they are, the more they can teleport, The most teleport things they can have is five, but can reload within seconds