The first chance you get to get this is on level 2. As you progress from the start, make sure you collect all the glowing items you come across, such as scrap metal etc.
When you leave the luggage conveyor and restore the power, in the same room get the code from the computer (0340 from memory). Use the passcode to enter the room (it's back down the stairs), collect the medical blueprints and the items in the room. Then you want to hold down B, and select the medical blueprints, select the parts and then press LB to craft a medical pack. Achievement unlocked.