What better way to teach your bad dice a lesson then throw them into the dungeon until they produce crits.

Supplies

Here's what you need to make this work. I've linked to some of the items (I'm in Canada, so some links point to Canadian sites).

Tools

3D Printer
UV Light for curing your print
Soldering iron
Wire strippers
Hot glue gun

Resources

Resin for the print. I used grey.
Solder
Cave and Gate 3D models
CR2032 Battery Holder
CR2032 Battery
Latching Tactile Tact Push Button Switch
LED and 100 Ohm resistor. I pulled mine out of the Assortment Kit I got on Amazon.
Heat shrink tubing
a pair of short wires, 4.5 cm
Paint Primer and Paints

Step 1: Print the Dungeon

Print your dungeon and gate.

Thanks to Terrain4Print for the original Rock formation which I modified into the dungeon.

Step 2: Prepare the Circuit

The kit I have didn't have a 51 ohm resister. I used 100 ohm instead, which isn't as bright, but should extend the life of the battery. Note the polarity of your LED, make sure it's connected the right way.

Tin (put solder on) all of your soldering points.
Solder the middle pin (Netative "-") of the battery holder to the latch switch.
Solder the resistor to one of the wires.
Solder the other side of the resistor to the other latch switch terminal.
Don't forget the heat shrink.
Solder the other wire to the edge pin (Positite "+") of the battery holder
Solder the LED to the two wires, making sure you solder Positive + (see diagram) to Positive + (directly to battery) and Negative - to Negative - via resistor and latch switch.

Step 3: Put It Together

This part is a little tricky. The hole for the latch switch is meant to keep the switch from popping out when clicking the switch, so it's a little tight. It does fit. If you're unsure, check that you can get the latch switch in before soldering everything together.

Use some hot glue to keep everything in place. As an added bonus, when it's painted it'll just look like rock.

Step 4: Paint It

The steps I used for painting I got straight from MisfitHobbies:

How To Paint Realistic Stone For Tabletop Terrain & Miniatures In Under 60 Seconds

Using the blood red paint, you can put a dollop of paint on a brush and flick it toward the inside of the dungeon. The results are extremely random! I ended up with some paint on the outside too, so do this at your own risk. I'm no paint expert and there are probably better ways to get splattered blood effects.

For the gate:

Prime using black
Use Gun Metal from the paint kit as a second coat
Apply some red wash to the base of the prison bars and corners to give it a bit of a rusting look.