Thermal bond epoxy. If that's your method of securing them to the wall, you just need to drug their food supply, and press them to the wall while they're still alive. Then, when they wake up, they'll start screaming and scratching on the walls. Some might even try to chew the skin from their bodies just to get off the wall. If that's the case, then you don't need to do anything but laugh to yourself as the blood from a dozen or so rats coats the wall in a fresh crimson gloss. Is anyone else disturbed at what I wrote there? It freaks me right the fuck out.