that you will find in the hallway leading to...

"You'll need a kind of "sardine can opener" which you can find in the hallway that takes you to"

"Espèce de" in this case means something that looks more or less like the object in question. In English, if you were to use "the kind (or the sort) of (something) which you find (somewhere)", it might mean that this is the type of the object that you usually find in that place. Not quite the same. This is the reason why I used quotation marks for "sardine can opener" which means to emphasize the fact that it is not really a can opener.

You could also use the sentence:
"You will need the sardine can opener type of thing, which you can find in the hallway that takes you to..."

Or more colloquially: "You will need the sardine can opener thingy which you can find in the hallway that takes you to..."

These might be more accurate...