Injection Molding & Drainage Fittings
Proudly Manufactured in Michigan
Pennington Plastics specializes in injection molding services, with expertise in drainage fittings, product design, mold design, and in-house manufacturing.
Injection Molding Services
Production molding with reliable equipment, consistent quality, and scalable output.
Drainage Fittings Manufacturing
Designed and produced with real-world drainage applications in mind.
Product Design Support
We help refine concepts for manufacturability, performance, and cost.
Mold Design & Development
From concept to tooling coordination — built for long-term production.
Turbo Taps (Custom Drainage Taps)
Manufacturer of Turbo Taps and custom drainage components.
Bring Your Product to Michigan
Already producing elsewhere? We can help transition manufacturing locally.
Why Choose Pennington
Drainage Industry Expertise
Built around real-world drainage experience to ensure practical, effective solutions.
Custom to Production Solutions
From concept and development to full production, we work with you every step of the way.
Michigan-Made Reliability for Contractors
Proudly designed and produced in Michigan with a focus on quality and reliability.
Four Generations of Drainage Innovation
Pennington Plastics is a Michigan-based injection molding company specializing in high-quality drain fittings and custom molded products. We offer complete services including product design, mold design, and full injection molding production using top-of-the-line equipment. Whether you already have an existing product that needs to be manufactured domestically or you have a new idea that needs to be developed from the ground up, our team can help bring it to life. Pennington Plastics was established to focus specifically on injection molding after years of designing custom drainage fittings and components, allowing us to move into in-house manufacturing and greater production control. Our roots run deep in the agricultural drainage industry, with our family business dating back to 1932 when Phillip Holzhausen Sr. and Jr. first began serving the industry. Today, the Holzhausen and Pennington families continue that legacy, representing four generations of experience in farm drainage and manufacturing.