Proto 1: Building the Saunosphere
After Proto 0 proved the concept, it was time to build something people could actually use.
We chose to start with the simplest configuration: a sauna. We called it the Saunosphere.
Why a sauna? Because it's forgiving. Temperature variations are fine. Rustic aesthetics are charming. The requirements are straightforward: heat, ventilation, seating. No water management, no complex systems, no precision fit and finish required.
Perfect for learning how to build these things right.
The Design Goals
For Proto 1, we had specific objectives:
- Validate the revised CAD (incorporating Proto 0 lessons)
- Test assembly sequence (can two people build it in a weekend?)
- Prove thermal performance (does it actually work as a sauna?)
- Document everything (photos, videos, measurements)
- Get user feedback (what do real people think?)
The Build
Materials Selection
We stuck with standard materials:
- Frame: 2x4 lumber (affordable, available everywhere)
- Exterior panels: 3/4" plywood (structural and weather-resistant)
- Interior: Cedar tongue-and-groove (traditional sauna material)
- Insulation: Mineral wool (heat-resistant, non-toxic)
- Hardware: Stainless steel (corrosion-resistant)
The cedar was a splurge. We could have used cheaper wood, but cedar is naturally resistant to moisture and heat, smells amazing, and gives that authentic sauna feel.
The Assembly Process
Day 1: Frame and Base
- Built the elevated base platform (6 legs, cross-bracing)
- Assembled the lower hemisphere frame
- Installed the floor panel
- Time: 6 hours, 2 people
Day 2: Panels and Structure
- Installed exterior panels (working from bottom to top)
- Built the upper hemisphere frame
- Connected upper and lower hemispheres
- Time: 8 hours, 2 people
Day 3: Interior and Insulation
- Installed mineral wool insulation
- Added vapor barrier
- Started cedar interior paneling
- Time: 7 hours, 2 people
Day 4: Finishing
- Completed cedar interior
- Built and installed benches
- Installed door and hardware
- Added ventilation (top vent, bottom intake)
- Time: 8 hours, 2 people
Day 5: Sauna Stove and Testing
- Installed electric sauna stove
- Wired electrical (hired electrician for this)
- First test heat-up
- Time: 4 hours + electrician time
Total build time: ~33 person-hours over 5 days
Not quite a weekend, but close. And this was our first build with the new design. We expect experienced builders could do it in 2-3 days.
What We Learned
The Good
Assembly sequence worked: The revised panel order made sense. No disassembly required.
Tolerances were right: The 1/8" gaps we designed in allowed for adjustment without being sloppy.
Thermal performance exceeded expectations: The nested sphere design meant we could use a smaller sauna stove (4.5kW instead of the typical 6kW for this volume).
It's beautiful: The cedar interior and spherical form create a unique, premium feel. Everyone who saw it was impressed.
Heat distribution is excellent: No cold corners, no hot spots. The convection creates even heat throughout.
The Challenges
Cedar is expensive: We spent $600 on cedar alone. For a DIY builder, this might be prohibitive. We're exploring alternatives (pine, hemlock, even plywood with a clear finish).
Interior paneling is time-consuming: Cutting and fitting tongue-and-groove cedar to a curved surface takes patience. We developed templates to speed this up.
Ventilation placement matters: Our first vent placement created too much draft. We moved the intake vent and added adjustable louvers. Much better.
Door design needs work: Our initial door was too heavy and the hinges struggled. We redesigned with a lighter frame and better hardware.
Electrical requires expertise: We can't expect DIY builders to wire a sauna stove. We need to provide clear guidance on when to hire professionals.
The Unexpected
It feels bigger inside than it looks outside: Multiple people commented on this. The spherical geometry creates a sense of spaciousness.
The elevated design is a feature: People love stepping up into the sphere. It feels special, like entering a different space.
Acoustics are interesting: The sphere creates unique sound properties. Conversations feel intimate. Music sounds great.
It's a conversation piece: Everyone who sees it wants to know about it. The form is distinctive and intriguing.
User Testing
We invited friends, family, and neighbors to try the Saunosphere. The feedback was overwhelmingly positive:
Temperature and Heat:
- "Heats up faster than my gym's sauna"
- "The heat is really even—no cold spots"
- "I can actually breathe comfortably" (good ventilation)
Comfort:
- "The benches are at perfect height"
- "I love the curved walls—feels cozy"
- "The cedar smell is amazing"
Aesthetics:
- "This is the coolest sauna I've ever seen"
- "It looks like a spaceship"
- "I want one in my backyard"
Concerns:
- "How much does it cost?" (price sensitivity)
- "Can I build this myself?" (confidence in DIY ability)
- "Where would I put it?" (space constraints)
These concerns are exactly what we need to address in our documentation and marketing.
The Numbers
Material costs: ~$3,200
- Lumber and plywood: $800
- Cedar interior: $600
- Insulation and vapor barrier: $200
- Sauna stove: $800
- Hardware and fasteners: $300
- Electrical: $200
- Misc (vents, door, etc.): $300
Labor: 33 person-hours + 3 hours electrician
Comparable products:
- Barrel sauna (similar size): $5,000-$8,000
- Traditional sauna shed: $8,000-$15,000
- Prefab sauna pod: $10,000-$20,000
Our material cost is 40-70% less than commercial alternatives. Even accounting for labor, there's significant value.
Market Validation
The Saunosphere proved there's a market for this.
Potential customers:
- Homeowners: Backyard wellness, property value
- Wellness centers: Unique offering, mobile deployment
- Resorts and hotels: Guest amenity, distinctive experience
- Gyms and spas: Recovery and relaxation
- Event rentals: Festivals, parties, corporate events
Revenue potential:
- DIY plans: $50-$100
- Pre-cut kit: $3,500-$4,500
- Fully assembled: $7,000-$10,000
- Rental: $200-$500 per event
The economics work for both builders and buyers.
What's Next
Proto 1 validated the Saunosphere as a viable product. Now we need to:
- Refine the design: Simplify interior paneling, improve door, optimize costs
- Create detailed plans: Step-by-step instructions, cut lists, assembly videos
- Develop kit packaging: How to ship pre-cut components efficiently
- Test alternative materials: Can we reduce costs without sacrificing quality?
- Build Proto 1.1: Incorporate lessons learned, time the build process
The Bigger Picture
The Saunosphere isn't just a sauna. It's proof that the Thiosphere platform works.
We've shown that:
- The design is buildable by non-professionals
- The thermal performance is excellent
- The form factor is compelling
- The economics are favorable
- There's market demand
This gives us confidence to move forward with Proto 2 (the Immosphere) and Proto 3 (the Agrosphere).
Each prototype adds complexity. Each one teaches us more. Each one expands what's possible with the platform.
The Community Response
We documented the build on social media. The response was incredible:
- 50,000+ views on build videos
- 500+ comments asking about plans
- 100+ people signed up for updates
- 20+ inquiries about purchasing
People are excited about this. They want to build their own. They want to be part of the community.
That's exactly what we hoped for.
Reflections
Building Proto 1 was hard work. Physically demanding, mentally challenging, occasionally frustrating.
But seeing it completed—seeing people enjoy it, seeing their reactions, hearing their ideas—made it all worthwhile.
This is real. This works. This matters.
On to Proto 2.
Next Post: Proto 2: The Immosphere Challenge
Previous Post: Another Decabillionaire? The Business Case for Open Source Hardware
Related: