just ask marcelo cardenas. >> this is one of the spots that we use for -- to hide the guns, the tattoo guns. i'm just right now making one. >> cardenas who is sharing his secrets because he is soon leaving for state prison and says he is not worried about punishment has a clever technique for hiding his homemade tattoo guns. the project involves hiding another piece of contraband, the hinge. in this case since the hole is still small, cardenas demonstrates how he uses a bar of soap to conceal one of the magnets used in the gun rather than the gun itself. >> the thing we do is put this inside the hiding spot. we break the soap so you can fit it. you have to take more time, but right now i'm just showing you. >> cardenas then peels small strips of paint off the wall and he moistens it with water. >> you use water because the water makes it stick and you put some on top of the soap like this, you know. you do that. then you have the wall covered up. >> well cardenas uses stealth to get around rules, erica haywood's disobedience is anything but covert. when managing haywood went from diffi