Your trip to Dr. Calvino’s workshop during "Through a Glass Darkly" will put you right next to a hidden stash (and an achievement/trophy) that is very easy to miss. There are clues hidden throughout Calvino’s workshop, but putting the pieces together requires a bit of patience. But we’re here to help you skip over all that.
Dr. Calvino’s Workshop
There are several pieces of information around Dr. Calvino’s lab that will lead you to the solution — there are two emails on the computer that hint at the solution and, if you watch Test.PHASE_2.lgv on the Looking Glass through to the end, you’ll see Calvino use his secret stash. The trick with the video is walking around to the other displays — specifically the one on the right, so you can see what he’s doing.
To get the secret stash open, you need to find Dr. Calvino’s Tumbler. It’s on top of the red toolbox to the right of the stairs when you first enter. Pick it up and carry it to the scale on the other side of the room (helpfully spotlit by a lamp). This will open a safe right next to the scale with two neuromods and Lorenzo Calvino’s Cabin keycard. Opening the hidden safe will also get you the "Coffee Break" trophy/achievement.
Lorenzo Calvino’s Cabin
You won’t be able to use that keycard until (at least) "Gathering Echoes." When you’re in Crew Quarters, you can find Dr. Calvino’s cabin in Crew Cabins B at the end of the hall on the left. Check his computer for some interesting audio files, then turn off the Looking Glass. You’ll see a safe behind the Looking Glass display. There’s a note Calvino left himself in front of the other computer in the room. His anniversary will give you the Calvino’s Safe keycode.
Smash the display and open the safe to find three more neuromods.