Illuminated Skull in Flames

Sized up from last flaming skull model (297mm tall)
Holes and tubes added for fitting recessed and concealed 5mm and 3mm LEDs
with central cavity to wire together from 5v power, or include
Arduino Nano or other small microprocessor to achieve pulsing/ fading effect per your tastes.

Printing:

Flame base (297mm high) is sized for 300mm Z height printer.

Set Tree Support overhang to 55 degrees, touching buildplate.
I recommend using a large support blocker on inside open cavity large enough to block wire tubes as well (pictured). Inside cavity and tubes do NOT need support, but I couldn't model that out of the design, and it would be a BEAR to remove support from well inside one of those tubes.
I like using 0.6mm nozzle and 2 walls for faster print. If you use .4 nozzle, go with 3 walls.

Jaw prints WONDERFULLY now (great with 0 infill), as I flattened the bottom for maximum printability. Support 55 degrees touching buildplate. Lower speed (25mm/s?)

Skull split in 2 for best printability.
Skull Main mating face has recessed portion so the 2 parts will mate together well, with less visible seam after priming and painting.
Recommend using support blocker for internal wire and neck tube cavities of skull, as well as the alignment pin holes. It doesn't need those and will be a bear to remove (learn from my experience). Ensure recessed bottom HAS supports.
The pictured print and screen shot worked well with 30% lightning infill (Cura).
-.2mm initial layer horizontal expansion (skull main and cap) to reduce elephants foot and less sanding of mate seams for painting.

Skull Cap: turn supports OFF. I used .3 initial LH, then .12 to minimize layer effect.

2 alignment pin holes for skull parts which use short length (5-6mm) of 1.75mm filament.

Recommend 10 or more line brim for Skull Peg Tube and print vertically as it is in the STL

Recommend translucent or clear filament for eyes and eye posts, intended to be lit from inside. 0.4 nozzle, they printed great without support. Sanding down Z seam on the tubes will help with insertion (don't random the seam). Extra set of eye tubes in file is for disposable blanks when priming/painting skull.

LIGHTING FUN!!!

8 rounded holes in flame base for LEDs (I wired 4 pairs of colors yellow, orange, red and 2x 2 pin RGB for dynamic effect).

Skull has channels for 2x3mm LEDs to eye holes to light the eyes (I set LEDs to sit inside the posts that hold the floating eyes for illuminating the sockets as well as eyes. Printed in clear filament for better translucency).
Roof of mouth also has hole for a 5mm LED to project light below the skull on the neat colored base. Wires are fed through the peg that mounts skull to flame base. I let LED rest outside of model to maximize light. It still isn't seen directly.

Overall goal was to illuminate the skull and base flames without external lighting, and without seeing the lights directly when viewed from fairly wide front angle. To be powered from standard 5v USB wall wart for full time display.

My preference was CLEAR LEDs which accented the silk filament MUCH better than diffused LEDs, which reduced the brightness and shine of the silk model.

Started with Amazon prewired LEDs, but then found that the resistors used were such high resistance (500 ohms?) as to reduce brightness (6mA, rather than the target 20mA from 5v source).
So I went with bare LEDs and soldered resistors near the female dupont connectors for GPIO pins. Not soldering resistors directly to LEDs allowed LED insertion into holes. 2v LEDs in series with smaller resistor near connector. 3v LEDs in parallel from larger resistors attached to connector wire.

Used PWM GPIO pins of Arduino for fading the 11 LEDs. 1 of the front flame holes needs a 3mm LED to fully recess/conceal. 5mm for all other flame lights. Used a few 2 pin RGB (3v) LEDs for extra color (Don't fade those in the code, just set pins to HIGH for them).

I used soldering iron in rear through-hole to expand and fit micro USB passthrough, making model more portable without risk of stress on the Arduino power pin wiring.

Lightly hot glued in channels where wires enter central cavity to hold LEDs in correct positions, and at USB passthrough after final testing. Taping wires along cavity for testing helps keep lights from slipping out. Make sure you like light positions and colors BEFORE HOT GLUING!!!

Highly recommend having fun painting or airbrushing the skull (before wiring and mounting of course). Mine just didn't come to life until I did.

You are welcome to message here for the Arduino Nano code for fading, then adjust for your microprocessor or pinout and preferences. I didn't want to make this model description any longer LOL