Does your manufacturing partner have the right custom capabilities for your prototype parts and volumes?
When you’re building custom prototypes, the quickest way to de-risk schedule and cost is to confirm—early—that a supplier’s process mix, material library, tolerances, envelopes, and finishing options match your parts. Don’t just ask “Can you make this?” Ask for concrete evidence on each of the checkpoints below.
Quick capability vetting checklist (TL;DR)
Use this 5-question checklist to choose a custom manufacturing partner for prototypes—each line includes what to verify so you can act fast.
- Capabilities fit (now + next):
- — Processes you need (CNC 3/4/5-axis, sheet metal, 3DP, injection molding)
- — Published materials, tolerances, build envelopes, and finishing catalog (anodize, chem film, plating)
- — Large-part capacity (if relevant), instant quoting/options
- Quality control/assurance:
- — ISO 9001:2015 in scope; downloadable certificate
- — Sample inspection report (FAI/in-process/final)
- — Material certs/CoC on request; clear NCR/CAPA process
- — GD&T competence; REACH/RoHS support if applicable
- Schedule & capacity proof:
- — Published lead-time options (fast-turn vs economy) with process-specific ranges
- — Recent OTIF history, stated cut-off times, and surge capacity (domestic + overseas)
- DFM & communication:
- — Proactive/automated DFM (draft, walls, tolerances) with annotated CAD/PDF
- — Defined feedback SLAs, single point of contact, in-platform issue resolution
- Compliance, sustainability & scale path:
- — Required finish standards (e.g., MIL-DTL-5541, anodize types) + traceability docs
- — Environmental policy/ISO 14001 or equivalent; waste/logistics practices
- — Clear path from prototype → low-volume/bridge without re-sourcing
1) Process coverage that matches your parts (today) and your path (tomorrow)
For most construction-adjacent prototypes—façade brackets, MEP fixtures, FF&E hardware, test jigs—you’ll typically need one or more of: CNC machining (3/4/5-axis), sheet metal, 3D printing, and/or injection molding. Favor partners who publish clear capability pages with examples, not just a generic list. For instance, it’s useful when a CNC page discloses speed (“as fast as 1 day”), tight tolerances (±0.0001”), finishing options (anodize, plating, chem film), and no MOQ—signals that they can handle precision one-offs and bridge volumes.
If your prototypes are physically large (architectural or equipment components), confirm build envelopes up front. Some networks advertise large-part CNC with assemblies up to tens of feet in length—handy for one-off fixtures or site hardware—along with published lead-time bands for those sizes.
Don’t overlook sheet metal capability for brackets, housings, and enclosures; look for material/finish breadth and whether the service is integrated with your other processes so you aren’t re-onboarding a second vendor just for bends and formed features.
2) Materials, tolerances, and envelopes—published and specific
Ask to see material libraries (e.g., Al 6061/7075, SS 304/316, engineering plastics) and published tolerance ranges by process. High-maturity partners document tolerances clearly (e.g., CNC microns-level for critical features; realistic, process-specific ranges for 3D printing) and will point you to selector tools or help articles when you’re deciding between polymers or printing processes.
For polymers and tooling, review injection-molding tolerance guidance (commercial vs. fine tolerances, feature-based considerations)—even at the prototype stage this prevents redraws later.
3) Speed options and capacity signals (not promises)
Prototype programs slip when “fast” is a black box. Look for clearly published lead-time choices at quote time (e.g., domestic fast-turn vs. overseas economy) so you can trade speed for cost per part, not per order. Vendors that expose a lead-time selection module in the quote help you plan batches and ship dates with fewer emails.
Also check for concrete speed claims by process—e.g., CNC parts as fast as 1 day or 3D-printed parts in ~24 hours—paired with realistic ranges. These aren’t guarantees, but they’re a good proxy that the network has both domestic and overseas capacity for spikes.
4) Finishing depth for construction-grade prototypes
Most construction-facing prototypes need surface protection or cosmetics. Your shortlist should include partners that offer conversion coatings and platings—for example Type II/III anodize for aluminum, chem film (chromate conversion) where electrical conductivity or paint-primer adhesion is required, and access to plating and black oxide when appropriate. Capability pages that state thickness ranges, standards (e.g., MIL-DTL-5541), and color options save back-and-forth during RFQs.
5) Evidence of “prototype-to-production” readiness (nice-to-have, big payoff)
Even if you’re only buying prototypes now, verify there’s a path to low-volume/bridge without re-sourcing—e.g., the same platform offers molding with quotes in hours, transparent DFM feedback, and mold-build visibility so you aren’t switching vendors at pilot. This continuity reduces rework and keeps your milestone dates intact.
Do they align with your compliance & sustainability needs?
Compliance isn’t just paperwork; it keeps prototypes shippable, installable, and insurable. If your parts touch electrical/controls or are destined for EU projects, verify your partner can document REACH (chemical safety) and RoHS (restricted substances in EEE) where applicable, and provide Certificates of Conformity (CoC) and material certs on request. Ask for a link to their quality/compliance page and sample docs.
For coated aluminum parts (common in brackets, housings, fixtures), ensure they can meet recognized specs such as MIL-DTL-5541 for chromate conversion (chem film) when conductivity or paint adhesion is required. Confirm finish callouts, thickness classes, and documentation expectations in the RFQ.
Sustainability is a recurring BUILD theme, so prefer partners with an environmental management framework (e.g., ISO 14001) and practical practices like material yield tracking, waste minimization, and optimized logistics. That alignment helps your own reporting and resonates with BUILD’s sustainability-forward readership.
What to request (copy-paste into your RFQ):
- REACH/RoHS statements (if relevant), CoC/material certs availability, and finish specs they certify to (e.g., MIL-DTL-5541).
- Environmental policy or certification (ISO 14001), plus notes on waste, recycling, or low-carbon shipping options.
Subtle backlink option: link quality assurance to a page that lists ISO 9001 and compliance statements (for example, Fictiv’s quality/ISO info).
Build your Supplier Scorecard (keep it simple and defensible)
Use a one-page scorecard so decisions are fast and auditable. Weight what matters for prototypes; keep a pass/fail gate for must-haves like ISO 9001.
Recommended weights (100 points total):
- Capabilities (25) – Processes, materials, tolerances, envelopes, finishing depth.
- Quality & Certifications (25) – ISO 9001 in scope; sample inspection; traceability; CoC/material certs.
- Lead Time & Capacity (20) – Published ranges, surge capacity, OTIF history.
- DFM & Communication (20) – Speed/clarity of feedback; issue-resolution process.
- Compliance & Sustainability (10) – REACH/RoHS support; finish standards; ISO 14001 or equivalent.
How to score (0–5 per line item):
- 0 = missing/unknown, 3 = adequate, 5 = best-in-class with proof (public pages, sample docs, data).
- Gate: If ISO 9001 is required and not in scope, stop—do not award.
Example (prototype façade bracket):
- Capabilities: 5 (CNC + sheet metal + chem film).
- Quality: 4 (ISO 9001 + sample FAIR, but limited PPAP).
- Lead time: 4 (published “as fast as” + domestic fast-turn).
- DFM: 5 (automated IM-DFM + <24–48h CNC DFM).
- Compliance/Sustainability: 3 (REACH/RoHS statements; ISO 14001 pending).
Tip: keep short notes per line (links to capability/quality pages or sample PDFs). If stakeholders ask “why this vendor?”, your scorecard explains it in one glance.
RFQ checklist for custom prototypes (copy-paste ready)
Include these items to reduce back-and-forth and get manufacturable quotes on the first pass:
Design & specs
- Native CAD + STEP, and a 2D drawing with critical GD&T (tolerances, datums, surface finish).
- Material + acceptable alternates; temper or grade where relevant.
- Finish spec (e.g., anodize Type II; chem film to MIL-DTL-5541 Class 1A/3, etc.).
Quantity & timing
- Prototype quantities and phasing (pilot/bridge volumes if anticipated).
- Target ship date(s); note expedite vs. economy preference by line item.
Quality & documentation
- Required inspection level (e.g., in-process + final), sample report format.
- Need for CoC/material certs and any special test results.
Compliance & handling
- REACH/RoHS applicability (if electronics/EEE or customer-mandated), labeling/packaging requirements, and any export/regulatory notes.
Logistics
- Ship-to, incoterms (if applicable), desired packaging (rack/protective wrap), consolidation instructions.
Mini case: Avoiding a Six-Week Slip With Better Vetting
Project context. A mixed-use development needed custom aluminum brackets to validate a façade detail before glass procurement. The team faced a tight two-week window between design freeze and a long-lead order.
What went wrong (first pass). The initial supplier claimed capacity but didn’t publish tolerances, finish standards, or lead-time bands. After award, DFM revealed wall-thickness issues that required redraws; plating turnaround was unclear. The prototype schedule slipped 10 days, threatening downstream dates.
Applying the five-question scorecard.
- Capabilities. The team shortlisted vendors with public process pages and clear tolerance/finish specs (anodize/chem film) plus large-part envelope notes.
- Quality. They requested ISO 9001 certificate PDFs and a sample inspection report to confirm CoC/material-cert practices.
- Schedule. They required published lead-time options (fast-turn vs. economy) and recent OTIF data.
- DFM & comms. They prioritized partners offering structured/automated DFM within the quoting flow.
- Compliance & sustainability. They asked for REACH/RoHS statements where applicable and confirmation that MIL-DTL-5541 chem film was available for conductivity and paint adhesion.
Outcome. With a scored shortlist, the award went to a partner that flagged draft and radius issues in DFM the same day, provided a chem-film spec that met the coating requirement, and confirmed a fast-turn domestic route. Brackets shipped three days early, keeping façade procurement on track.
(This case is anonymized and method-focused; swap in your own project specifics if you publish an example.)
Choosing a Manufacturing Partner – FAQs
What certifications matter most for prototype suppliers?
Start with ISO 9001:2015 as your baseline for a formal quality management system. Ask to see the certificate PDF, check its scope/dates, and request a sample inspection report.
How fast can I realistically get prototypes?
Look for providers that publish process-specific lead-time ranges so you can trade cost vs. speed. As an example of public claims to look for, Fictiv lists CNC parts “as fast as 1 day” and 3D-printed parts “as fast as next-day.” Treat such claims as benchmarks to request—not universal guarantees.
What is OTIF and why should I ask for it?
On-Time-In-Full (OTIF) combines schedule and completeness: did the order arrive by the promised date and in the promised quantities? Asking for recent OTIF helps quantify delivery reliability across prototype batches.
Which compliance docs should I request?
For EU-bound work or customer mandates, ask for REACH and (where electronics/EEE are involved) RoHS statements. For coated aluminum, specify MIL-DTL-5541 chromate conversion (“chem film”) requirements in your drawings/RFQ.
Should I stay with the same partner from prototypes to low-volume?
Often yes: continuity preserves DFM knowledge, speeds tooling decisions, and shortens iterations—especially where the partner provides in-platform/automated DFM that scales from quote to production.
Conclusion
Choosing a custom manufacturing partner for prototypes doesn’t have to be guesswork. Use the five-question checklist, score candidates with the Supplier Scorecard, and include the RFQ checklist to eliminate back-and-forth and surface true capability, quality, schedule, and compliance. For readers who want a concrete example of the kind of public proof points to look for, review a capability page with published tolerances, lead-time ranges (e.g., “as fast as 1 day” for CNC), and visible quality credentials—then apply the same standard to any vendor you evaluate.
