The Golden Ratio Cloche: Why We Redesigned the Dome

Why Redesign a Working Dome

Our first dome design worked. It maintained humidity, housed the electronics, and looked decent on a shelf. So why throw it out and start over?

Because "works" is not the same as "right."

The original dome was designed around manufacturing constraints — panel sizes that fit a standard 3D printer bed, wall thicknesses that printed reliably, a base footprint that accommodated the electronics. These are valid constraints, but they produced a shape that was functional without being intentional.

The golden ratio cloche is intentional. Every proportion serves a purpose.

The Math Behind the Shape

The golden ratio — approximately 1.618 — appears throughout nature, and it shows up in mycology more than most fields. Mycelium branching patterns follow golden ratio angles. Mushroom cap proportions in many species approximate golden ratio relationships. Even the spiral patterns of some fruiting bodies reflect this mathematical constant.

We used this ratio to define the fundamental proportions of the new dome:

The dome height to base diameter ratio is 1:1.618. This is not decorative — it creates an internal volume where the warm, humid air rising from the substrate naturally circulates before exiting through the upper vent caps. The original dome's proportions created dead zones where stagnant air accumulated. The golden ratio proportions eliminate them.

The growing chamber to plenum ratio follows the same constant. The space where mushrooms fruit versus the space reserved for air circulation and electronics is divided at the golden ratio point. This gives the substrate block maximum growing volume while maintaining the airflow geometry that the PID controller needs to hold stable humidity.

The vent cap openings are sized proportionally as well. Too large and humidity escapes faster than the humidifier can replace it. Too small and CO2 builds up despite the FAE fan. The golden ratio sizing hits the sweet spot where passive ventilation supplements the active fan cycling.

Parametric by Design

The entire cloche is parametric in OpenSCAD. Every dimension derives from a small set of base constants — the golden ratio, the target internal volume, and the 3D printer bed size constraint. Change any constant and the entire model regenerates consistently.

This matters for the community. Want a larger dome for multiple substrate blocks? Change the base diameter constant and everything scales proportionally — vent caps, wall thickness, base housing, substrate platform. The golden ratio relationships hold at any scale.

Want to print on a smaller bed? Adjust the panel size constraint and the dome automatically subdivides into more panels with updated clip geometry. The split-dome variant — designed for printers with beds under 220mm — uses the same parametric constants as the full dome.

What Changed in v0.1.0

The v0.1.0 release on GitHub includes everything:

• Dome shell — Full and split-dome variants with golden ratio proportions
• Vent caps — Proportionally sized for optimal passive airflow
• Base housing — Redesigned to accommodate the ESP32, MOSFET drivers, and wiring with better cable management
• Substrate platform — Elevated growing surface with drainage channels sized to the golden ratio grid

All STL files are available for immediate download from the void-blueprints releases page. A GitHub Action automatically packages the STL exports whenever we tag a new release, so the downloads are always current.

Print Settings That Work

We have validated the golden ratio cloche on multiple FDM printers. Here is what we recommend:

• Material: PETG for humidity resistance, or ABS if you have an enclosure
• Layer height: 0.2mm for a good balance of speed and surface finish
• Infill: 15% gyroid — strong enough for the dome panels without excessive material use
• Walls: 3 perimeters minimum for moisture resistance
• Supports: Tree supports for the clip geometry, easily removed after printing

The full dome prints in approximately 18-20 hours total across all panels. The split-dome variant adds about 4 hours due to the additional seam geometry.

Form Follows Function Follows Nature

The golden ratio cloche is not a cosmetic upgrade. It is a functional redesign that happens to produce a more beautiful object — because the same mathematical relationships that optimize airflow and humidity control also produce proportions that humans find naturally appealing.

That is what happens when you design with nature's math instead of against it. The dome looks right because it is right.

Download the STL files and see for yourself. The build page has everything you need to print your own.

The golden ratio cloche (v0.1.0) is released under CERN-OHL-P-2.0. Fork it, modify it, improve it.