Got a brig up and running:
#1: The entrance, just off the dropshaft/ladderway on Deck 7:

#2: Just inside the entrance, we have a weapons & explosives scanning room, with an observation window on the right. I could wire the doors up so that an external switch would be required to open them, but I don't want anybody trapped inside, so for now, pressure plates are conveniently located on the floor near each doorway:

#3: Once through the scanning room, visitors must leave all metal items in the provided chest (at right) before proceeding through the metal detectors (at left). Glimpsed through the glass on the right is the reception desk area, and on the far right, 2 switches, green and red. More about them below:

#4: Situated on the opposite side of the scanning room's observation window, this station has access to 2 switches. These switches govern the behavior of the scanning room's inner door (seen in picture #2). When inactive, the switches allow normal, pressure plate-based door operation. When the green switch is active, the inner doors remain open. When the red switch is active, the inner doors are forced closed. The red switch overrides all other signals, whether they be from the pressure plates or the green switch. In the distance at right, the doors to the maximum security cells can be seen.

#5: Minimum-security detention cells:

#6: Inside the maximum security cellblock, looking towards the entrance doors (seen in picture #4). On either side of the door, two buttons must be pressed simultaneously* by two people to open the doors.

All cells are equipped with a sleeping cot and a toilet.
* For sanity's sake, the buttons are labeled "1" and "2". Button #1 has a slight delay on it, so if you're quick enough, you can actually press button 1 and then quickly press button 2, and the doors will open. This, however, is greatly complicated by lag - visitor be warned!