How PRECISION Helped “The One Glass” Turn a Great Idea into a High-Performing Drinking Tumbler
The Challenge
More than 15 years ago, entrepreneur Wendy Weir launched an innovative loose-leaf tea travel mug inspired by her travels in China. The concept resonated immediately: a stylish, glass-lined tumbler that allowed users to enjoy premium tea on the go without drinking loose leaves.
As demand grew, so did a few quality issues. The Tumbler’s crucial connection points and seals were challenged with the human crafted inner glass and were showing leaks that frustrated consumers. These leaks were a deal breaker for a tumbler to be recommended or purchased again.
The double-wall design also created cleaning challenges. Product buildup between layers led to hygiene concerns and frustrated customers.
Without an engineering or manufacturing background, Wendy relied on a Chinese factory specializing in glass, stainless steel, and plastics to bring her idea to life. Production was largely manual, making consistency difficult. Communication gaps and cultural differences made it even harder to enforce quality improvements.
Wendy needed more than a supplier; she needed a partner who could bridge the gap between her idea and execution.
The PRECISION Approach
Wendy turned to Precision Injection Molding for help.
Working closely with co-founder Paul Tontsch, she gained a partner who could operate both strategically and hands-on. Paul traveled with Wendy to China and worked directly on the factory floor, observing how the product was being assembled. He had several partner factories based in China and knew how to work efficiently with them.
Paul quickly identified the root issue:
Too much reliance on manual processes to achieve tight tolerances required for a liquid-containing product.
From there, Paul put his expertise into action. He:
- Identified critical process improvements to reduce leaks.
- Worked directly with factory leadership.
- Presented cost-of-failure data to drive accountability.
- Negotiated credits and corrective actions.
For the first time, Wendy had someone who could both speak the language of manufacturing and advocate for her business.
Engineering for Performance and Consistency
As the factory modernized its processes, PRECISION helped Wendy take full advantage of their capabilities.
Together, they:
- Defined critical tolerances for all key components recognizing that even fractions of a millimeter impact sealing performance.
- Translated real-world use (boiling water, daily handling, portability) into engineering requirements.
- Ensured repeatability at scale, so every unit performed consistently, not just the first off the line.
This shift, from concept-driven design to engineering-driven manufacturing, was a turning point.
Redesigning for Real-World Use
Customer behavior revealed another key issue: the product needed to be easier to clean.
Users were putting everything from tea to oats into the tumbler, and the sealed double-wall design wasn’t practical. The 2 layers needed to come apart for cleaning and with Wendy’s idea of how this could be achieved, Wendy, Paul and the factory worked together to find a solution.
Working collaboratively in China, the team developed a new design, including:
- Twist-off bottom – Allowed the tumbler to fully separate for cleaning.
- Safe, intuitive assembly – Designed to prevent user error while handling boiling liquids.
- New seal system – Re-engineered to support the modular design while maintaining leak-proof performance.
PRECISION delivered detailed engineering drawings to ensure the new design could be manufactured consistently.
The redesigned, dishwasher-safe model launched in 2023.
The Results
Near-Zero Complaints at Scale
With improved tolerances and design:
- ~20,000 units produced
- Virtually no performance issues
- Dramatically improved durability and reliability.
Most importantly, the product now aligns with how customers actually use it.
“This is the best performing product that I’ve had out of all the versions. I cannot say enough about the quality of this new model.”
— Wendy Weir
Reduced Stress. Increased Confidence.
PRECISION didn’t just fix the product; it transformed Wendy’s business. She now experiences:
- Lower returns reduced financial pressure.
- Expert guidance improved decision-making.
- Stronger factory relationships increased control.
Wendy happily states, “Do I trust him? I trust him with my life.”
A Long-Term Engineering Partner
PRECISION’s role evolved beyond troubleshooting to ongoing innovation:
- Supporting new product concepts.
- Acting as a bridge between entrepreneurial vision and manufacturing reality.
- Navigating cultural and operational challenges in offshore manufacturing.
Why Innovators Choose PRECISION
Wendy highlights three key reasons:
- Deep expertise across design, plastics, and complex assemblies.
- Ability to ask the right questions of both founders and factories.
- Proven experience navigating global manufacturing environments.
If you have a product that needs to handle hot and cold liquids, withstand daily use, or simply “just work” every time, PRECISION can help you get there reliably, repeatably, and with the right partner at your side.
About Precision Injection Molding
Precision Injection Molding goes beyond producing plastic parts. We partner with innovators to:
- Turn product ideas into manufacturable designs.
- Engineer tolerances and assemblies that protect your brand.
- Work directly with domestic and offshore factories to ensure consistent quality.
If your product needs to perform reliably under real-world conditions, PRECISION helps you get there.
Client Snapshot
Client: Wendy Weir, Founder of The One Glass (formerly Libre Tea).
Product: Double-walled loose-leaf tea tumbler with glass insert and plastic exterior.
Services: Manufacturing consulting, tolerance engineering, seal design, factory liaison.