Custom OEM shower enclosure manufacturing is a structured process that transforms a brand's specifications into a delivered product. Understanding this process helps buyers set realistic timelines, avoid common pitfalls, and specify products that can be manufactured efficiently without sacrificing quality. This guide walks through each stage from initial inquiry to final delivery. Learn more in our OEM guide.
Stage 1: Inquiry and Specification Review
The process begins with the buyer submitting a product inquiry. A complete inquiry includes: target market and applicable standards (EN 14428, ANSI Z97.1, AS/NZS 1288), desired configurations (sliding, pivot, fixed panel), glass specifications (thickness, type, coating), hardware preferences (material, finish, mechanism), packaging and shipping requirements, and target volume and timeline. Learn more in our En 14428 guide.
The manufacturer reviews the inquiry against their production capabilities. Not every specification can be manufactured on existing tooling — some configurations require custom molds, dies, or jigs. The manufacturer identifies which specifications are standard (available on existing tooling), semi-custom (minor modifications to standard tooling), and fully custom (new tooling required).
A quotation is issued based on the specification review. The quotation includes per-unit pricing at different volume tiers, tooling costs for custom configurations, estimated lead time, and sample availability. Tooling costs are typically amortized across the first production run, reducing the effective per-unit cost.
Stage 2: Design Review and Engineering
Once the buyer accepts the quotation, the manufacturer conducts a detailed design review. This stage involves close collaboration between the buyer's design team and the manufacturer's engineering team.
Technical drawing review: The manufacturer produces detailed technical drawings for every component: glass panels, hardware, seals, frames, and packaging. The buyer reviews these drawings for dimensional accuracy, material specifications, and assembly logic.
Glass specification: The glass type, thickness, tempering standard, edge finish, and any drilling or cutout locations are specified on the technical drawings. For tempered glass, all cutouts and edge work must be completed before tempering — no modifications are possible after the tempering process. Learn more in our Tempered Glass guide.
Hardware selection: The hardware is selected based on the glass thickness, door weight, and operating mechanism. Hinges, rollers, handles, and seals are specified with part numbers, materials, and finishes. The manufacturer may recommend alternatives if the buyer's specified hardware is not compatible with the glass configuration. Learn more in our Glass Thickness guide.
3D modeling: For complex configurations, the manufacturer produces 3D CAD models that the buyer can review for fit, clearance, and aesthetic alignment. This step is especially valuable for projects with non-standard geometry or tight space constraints.
Stage 3: Prototyping and Sample Approval
Before committing to full production, the manufacturer produces a prototype sample for the buyer's evaluation. This stage confirms that the design translates from drawings to a physical product that meets the buyer's expectations.
Sample production: The manufacturer produces one complete set (all panels, hardware, seals) using production-grade materials and processes. The sample is built to the same quality standards as the production run, not a simplified mockup.
Buyer evaluation: The buyer inspects the sample for dimensional accuracy, glass quality, hardware function, finish consistency, and assembly ease. If the buyer is an installer or distributor, they may assemble the sample to verify the installation process.
Sample revision: If the sample does not meet expectations, the manufacturer produces a revised sample addressing the identified issues. This revision cycle typically takes 7 to 14 days. Most projects require one to two revision cycles before approval.
Sample approval sign-off: Once the buyer approves the sample, they sign a sample approval form that locks the specification for production. Changes after sample approval may require new tooling or additional lead time.
Stage 4: Tooling and Setup
With the sample approved, the manufacturer prepares the production tooling.
Existing tooling: For standard configurations, the tooling is already in place. Setup involves loading the correct glass sizes, adjusting the production line for the specified thickness, and confirming the hardware configuration.
Modified tooling: For semi-custom configurations, minor modifications to existing tooling are required. This might include adjusting a glass cutting template, modifying a seal profile, or changing a hardware mounting jig. Modification time is typically 3 to 7 days.
New tooling: For fully custom configurations, new molds, dies, or jigs must be fabricated. This is the most time-consuming stage, typically requiring 15 to 30 days depending on complexity. New tooling costs are a separate line item in the quotation.
Tooling validation: After setup or fabrication, the manufacturer produces a small test batch (5 to 10 units) to confirm that the tooling produces parts matching the approved sample. The buyer may request to inspect this test batch before full production begins.
Stage 5: Production
Full production follows a defined sequence for each enclosure set:
Glass processing: Raw float glass is cut to size, edge-worked (polished, beveled, or arris as specified), drilled (if required for hinges or handles), and tempered. Tempering transforms the glass into safety glass with a surface compression that is four to five times stronger than annealed glass. The tempering process takes approximately 45 minutes per batch. Learn more in our Safety Glass guide.
Quality inspection: Each tempered panel is inspected for dimensional accuracy, surface defects, and tempering quality. The manufacturer uses polarized light inspection to verify the stress pattern — an even pattern indicates proper tempering; uneven patterns indicate defective glass that must be rejected.
Hardware assembly: Hardware is pre-assembled onto the glass panels where possible, reducing on-site installation time. Hinges, handles, and rollers are mounted at the factory using calibrated torque tools to ensure consistent fastening force.
Cleaning and packing: Assembled panels are cleaned, inspected one final time, and packed into ISPM 15 compliant crates. Each crate contains a packing list, assembly instructions, and hardware identification sheet.
Production timeline: A standard production run of 100 to 500 enclosure sets takes 25 to 35 days from glass cutting to packed crates. Custom configurations add 5 to 10 days for tooling setup.
Stage 6: Quality Assurance and Certification
Before shipment, the manufacturer conducts final quality assurance that includes dimensional verification, hardware function testing, and packaging integrity inspection.
Certification documentation: The manufacturer provides certificates of conformity for the glass (tempering certificate, safety glass marking), hardware (material certificates, plating thickness reports), and overall product (test reports per the applicable standard). These documents are essential for building inspections and regulatory compliance. Learn more in our Safety Glass guide.
Third-party testing: For products requiring third-party certification (SGCC for the US market, CE marking for Europe), the manufacturer arranges testing at an accredited laboratory. Test samples are drawn from the production batch, not from pre-production samples. Learn more in our SGCC guide.
Pre-shipment inspection: The buyer or their agent may conduct a pre-shipment inspection at the factory. This inspection verifies that the production batch matches the approved sample in quality, specifications, and packaging. Industry-standard pre-shipment inspection protocols (AQL sampling) are typically used.
Stage 7: Shipping and Delivery
The final stage is shipping from the manufacturer's factory to the buyer's warehouse or project site.
Shipping terms: Common Incoterms include FOB (Free on Board — the manufacturer loads the container at the port of origin), CIF (Cost, Insurance, Freight — the manufacturer arranges shipping to the destination port), and DDP (Delivered Duty Paid — the manufacturer handles all logistics to the buyer's door).
Container loading: Crates are loaded into ocean containers using the methods described in our shipping guide. The manufacturer provides a loading plan showing crate positions within the container. Shipping guide
Documentation: Shipping documents include the commercial invoice, packing list, bill of lading, certificate of origin, and any required import permits or certificates. These documents must be accurate and complete — errors in customs documentation can delay clearance by weeks.
Typical Timeline Summary
Inquiry to quotation: 3 to 7 days
Design review and engineering: 7 to 14 days
Prototyping and sample approval: 14 to 28 days
Tooling setup: 3 to 30 days (depending on customization level)
Production: 25 to 35 days
Shipping (ocean freight): 15 to 45 days (depending on destination)
Total: inquiry to delivery: 70 to 160 days depending on complexity and destination.
For a detailed consultation on your custom enclosure project, contact our OEM team.
Conclusion
The OEM process is a structured collaboration between buyer and manufacturer. Understanding each stage — from specification review through prototyping, tooling, production, certification, and shipping — helps buyers set realistic expectations, avoid costly delays, and specify products that can be manufactured efficiently. The investment in proper specification and prototyping pays dividends in production quality and timeline reliability. Learn more in our OEM guide.
