Slasher Spheres: Jason Voorhees

I have always loved both the creature-catching world of Pokémon and the gritty slasher atmosphere of Friday the 13th. There is something satisfying about blending two completely distinct pop-culture universes together, and seeing other themed display spheres in the community inspired me to build one for my own shelf.

The result is the Jason Slasher Sphere. It translates Jason's iconic hockey mask—complete with the brow chevrons, ventilation ports, and the classic battle-worn axe damage notch—onto a standardized spherical display piece with an integrated flat footing so it never rolls off your desk.

FEATURES

• Multi-Part Snap Assembly: Interlocking shells, alignment core, and detail chips let single-extruder printers achieve a clean multi-color display piece with zero mid-layer pauses.

• Anti-Roll Base: The bottom hemisphere features a built-in flat footing, keeping the sphere stable on any level shelf or tabletop without a separate display stand.

• Heavy-Duty Alignment Core: A large rectangular internal alignment peg provides maximum shear strength and locks both hemispheres together without twisting.

• 100% Support-Free: Hemispheres and dividing bands print flat-face down directly against the build plate for clean exterior curves without support scars.

• Open Source: Fully parametric OpenSCAD source files and parameter presets available on GitHub under Cold Front Forge.

MODEL VARIANTS & FILES

Files are provided as individual single-color STL meshes ready for plate sorting:

• Top Shell (jason-ball-top.stl): White upper hemisphere with recessed facial feature pockets and axe damage groove.

• Bottom Shell (jason-ball-bottom.stl): Black lower hemisphere with flattened base.

• Center Dividing Ring (jason-ball-ring.stl): Silver equatorial band.

• Core Alignment Peg (jason-ball-filler.stl): Internal rectangular alignment block.

• Front Button Assembly (jason-ball-front-ring.stl & jason-ball-button.stl): Two-piece actuator and bezel.

• Face Detail Chips: Individual inserts for ventilation ports (black), brow chevrons (red), and axe notch (silver).

RECOMMENDED PRINT SETTINGS

• Orientation: Flat on the bed, equator face down (no supports needed). Core peg printed flat on its side.

• Material: PLA or PETG.

• Layer Height: 0.20 mm.

• Wall Generator: Arachne (mandatory to resolve thin perimeters around face pockets).

• Wall Loops: 3 to 4 walls for solid feature backing.

• Infill: 15% Gyroid for hemispheres; 100% solid infill for all small chip inserts to prevent snapping during insertion.

• Seam Position: Back / Rear (keeps seams off the front face and button housing).

• Elephant Foot Compensation: 0.15 mm (critical for the 0.05 mm tolerance chip pockets).

• Brim: None required on clean PEI.

ASSEMBLY INSTRUCTIONS

1. Install mask chips first: Press the black ventilation plugs, red chevrons, and silver crack insert into the matching pockets on the top white shell.

2. Build the internal core: Slide the rectangular filler peg into the bottom shell socket, slide the center ring over the peg, and seat the top shell down firmly.

3. Assemble the front button: Press the red button into the silver bezel, then press the combined unit into the front equator opening.

4. Adhesive note: While parts are engineered to hold under friction alone, a tiny drop of CA glue inside small chip pockets or the front bezel ensures long-term display durability.

Designed by Cold Front Forge. Open-source under Creative Commons (CC BY-NC-SA 4.0).