The third thing you'll need is something made of zinc. This is where it starts getting complicated.

The object itself doesn't matter, just as long as it's made of zinc.

Zinc isn't as common as copper, so it'll be in a more secure location.

Check out the areas of the base that would be used to store and study metals.

In the geology lab, of course! The only problem is that you can't take it off its pedestal for some reason.

There might also be a guard here - follow these hints for help dealing with him.

You may have forgotten it, but we still have the research notes from upstairs - they may prove useful here.

The second page of the notes mentions metals hovering and generating shields; that sounds familiar.

It also mentions certain substances that can disable these shields - for zinc, that's 'chlorure of sodium.'

Sodium chloride! Otherwise known as just... salt.

The kind you'd put on your food.

Take the salt shaker from the lunch room, then use it to 'swap places' with the zinc.

The last thing you need is... a lemon.