I've had mazes work pretty well. Well, to call it a maze might be overkill, but a hallway or two lined with traps, yeah. You might have to put additional walls to deter them from eating through a wall that blocks their direct progress though.
Hah, pretty much pillowtalk's response is my boat. Yeah it can be a bit of a grind but when it starts feeling like a grind I stop playing and come back later. Stopped right now after I hit the 2nd research upgrade.
The collection book is also pretty deviously great. I've barely been recycling schematics and survivors because of it.