Once you get access to the Recycler and the Fabricator, you will be able to start building things out of the material you recycle. Eventually, you'll be able to Fabricate Neuromods - once you find the plan.
The plan is located in a private office in the Fabrication section of the Neuromod Division. All you need to access this is the Huntress Boltcaster (found here) and the Volunteer Quarters Door Code (found here).
After retrieving the Boltcaster and Volunteer Quarters door code, backtrack to the Neuromod Division. Climb to the second floor, either via the elevator shaft or the wall in the foyer (using the GLOO Cannon, of course) and use the code on the Volunteer Quarters door.
You'll find yourself in a very dark, open room. Enter the very first office on your left. Behind the desk, you will see a small maintenance door. Open it and move inside. From there, you will be in a large shaft. Use your GLOO Cannon to climb to the second floor of this shaft, and proceed through the passageway.
You'll emerge in an office with two dead bodies. You are now in the Fabrication wing of the Nueromod Division. Leave through the window on the left by breaking the glass. You will find yourself on the second floor overlooking an open area. Be careful not to make too much noise in this room, as it is populated by a large alien (a telepath) that is very hard to defeat.
Still on the second floor, you will see a second office down the walkway. This is Halden Graves' Office. The door is locked. In order to unlock it, you will need to climb on the ledge that looks in the window of this office. Break the window and then shoot the manual override switch with your Huntress Boltcaster. This will unlock the door. You can also do this through a hole in the ceiling.
Climb back around, staying on the second floor and avoiding the Telepath, and enter Graves' Office. Once inside, move to the right, where you will find a large table with the Neuromod Fabrication Plans.
Don't be too excited though, fabricating a Neuromod is very expensive. If you do it too often, you will need to come back to Graves' Office and renew your license at his computer.