About the ModelExperience the mesmerizing magic of 3D printing with this satisfying passthrough mechanical toy! Watch as the twisted, star-shaped central shaft seamlessly spirals all the way through the spherical shell, creating an incredibly smooth, continuous mechanical motion.

Designed by a Mechanical Design Engineer, this model is a perfect combination of geometry and precision engineering. The assembled sphere rests comfortably in your hands, making it a premium anti-stress desk toy.

Premium feel & smart design:

Dimensions: The model is designed with a 80 mm sphere diameter for a substantial, premium feel in the hand.

Scalability: Both parts can be easily scaled up or down together in your slicer to fit your preferences or build plate size.

Effortless Insertion: To ensure the shaft enters the sphere effortlessly from either side, the model features smart 1 mm chamfers on both ends of the shaft and the hole openings.

Flush Fit: The top and bottom openings feature specially designed contoured recesses, allowing the ends of the shaft to sit perfectly flush with the sphere's surface for a truly seamless look when fully inserted.

Optimized Base: The base of the sphere has a clean flat cut with a 2 mm fillet for optimal bed adhesion.

Tactile Comfort: The rest of the geometry is softened with perfectly smooth 0.5 mm fillets for a flawless tactile grip and reduced friction.

Print SettingsThis model is highly optimized for flawless FDM printing and a satisfying mechanical fit.

Material: PLA, PETG, or Silk PLA (Silk filaments look absolutely stunning with the curved reflections of the spherical shape!).

Orientation: Print the central shaft standing vertically. Print the single sphere with the flat cut facing the build plate, hole pointing directly upwards.

Supports: Absolutely no supports for the central shaft! The sphere prints beautifully without internal supports.

Infill: 10-15% (Gyroid or Cubic).

Perimeters/Walls: 3 to 4 walls for structural rigidity, ensuring the internal splines remain strong during the passthrough action.

Engineering Tips for a Perfect Print:

Bridging the Recesses: The contoured recesses at the poles create small arch overhangs. Pro Tip: Ensure your Bridging settings are enabled in your slicer. With a well-tuned cooling fan, your printer will easily bridge these small gaps.

Perfect Tolerances: The model is engineered for a buttery-smooth sliding action. Ensure your printer is well-calibrated for dimensional accuracy.

Mastering the Bottom Fillet: Because the base of the sphere features a 2 mm fillet, the first few layers have a steep overhang. Print the first 3-5 layers very slowly (e.g., 15-20 mm/s) with maximum cooling to ensure it prints cleanly.

Z-Seam Alignment: For the smoothest rotation, set your Z-seam to Random or carefully align it to the sharp inner corners of the star profile.

Support the Designer!If you enjoyed my free models (Cone and Hourglass), please consider supporting my work by purchasing this premium Sphere! Your support motivates me to keep creating high-quality engineering designs for the community.