3-Axis Skull Mod for 12ft Skeleton

The 12ft skeleton (Skelly) from Home Depot is an impressive decoration, but needs an extra kick to make it truly incredible!!!

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I've been in the world of Halloween based animatronics for over 10 years and have even made a name for myself with my MonkeyBasic software, now available through

So it only made sense that once I got my hands on one of these that I would cut it open!

This is my first time creating the 3-axis movements (plus jaw) from scratch, typically someone else beats me too it so I decided to combine my 3D printing ability, my limited mechanical knowhow and give this a whirl. I'm quite happy with the results!

I'm pretty sure this will void the warranty on your Skelly! LOL

This project covers the construction of the mechanical parts and installation into the skull. It does NOT cover the electronics or programming of the routines.

I do not recommend doing this project if you are not comfortable with servos or animatronics. I'd recommend starting with a smaller 'normal size' skull first. Like those available from or

WARNING: You will be cutting large holes in your plastic skull as well as separating the jaw from the skull. You will also need to cut the metal pipe that protrudes out of the neck a small amount so it doesn't interfere. Be careful and make sure you are comfortable with this!!!

NOTE: This is not meant to be water-resistant!!! If you plan to keep you Skully out for the month of October, this may not be meant for you... or try to find a 2nd head you can swap in!


  • 1 × 3D Printed Parts (see external link to Thingiverse) For printing the parts of course!
  • 3 × Hitec HS-805BB w/ included Servo Arm and Hardware Hitec Giant Servos for Yaw, Roll & Pitch
  • 1 × Hitec HS-425BB w/ Servo Arm For the Jaw movement
  • 1 × Thrust Needle Roller Bearings with Washers 20mm Bore, 35mm OD
  • 1 × Flat Steel Bar (cut into 2 pieces) 1/8" thick, 1/2" wide

View all 13 components

View project log

  • 1
    Interface assemble

    Start with the (white) 3D printed part called "Skull_Mech_V3_Interface" This connects to the neck of the skeleton.

    1. Make sure the shaft is smooth, sand it down a little if needed.
    2. Slide the thrust needle bearing assembly down (washer, bearing, washer)
    3. Screw in the two M3 screws (thread length around 12mm) at the top of the part. These will tighten the rotation servo onto this part later. Don't tighten the screws.
  • 2
    Rotation Servo installation

    You will be using the 1st level (blue) 3D part labeled "Skull_Mech_V3_1stLvl"

    1. Remove the servo arm (and screw) from the servo. 
    2. Position the Rotation servo as shown and attach with the included hardware.
      1. There are holes in the 3D model for aligning the servo screws.
  • 3
    Tilt Servo Installation

    Still using the 1st level (blue) 3D printed part.

    1. Install the servo arm shown (you may need to remove and adjust its position later on).
    2. Position the Tilt servo as shown and attach with the included hardware.

View all 21 instructions

Enjoy this project?



sbbbugsy wrote 12/24/2021 at 04:06 point

Any chance that you will make this a kit?

  Are you sure? yes | no

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