Prototype Companies: How to Choose the Right Partner

Prototype companies fall into fabrication shops, engineering-led prototype developers and full product development partners. Here is how to tell them apart, screen a shortlist and read a quote.

January 8, 20195 min read

Written by Konstantin Dolgan, Ph.D., NPDP

Founder & CEO, Product Development Engineer

Published January 8, 2019Updated September 2, 2026

Prototype companies fall into three groups: fabrication shops that make parts from your files, prototyping bureaus that make parts and advise on process, and product development firms that design the thing and then prototype it. Picking the wrong group is the most common reason a first prototype answers no useful question.

This guide explains what each type of shop does, how to screen a longlist down to two finalists, what a complete quote contains, what prototypes realistically cost, and the warning signs that should end a conversation.

A machinist and a client reviewing a machined prototype part together at a CNC shop bench — The right prototype partner asks about the test plan before quoting the part.

The prototype types a good prototype company should be able to build and advise on.

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The three kinds of prototype companies

Type	What they deliver	Best when	What they will not do
3D printing bureau	Printed parts from your STL or STEP files, often overnight	You need form and fit checks fast and cheaply	Tell you the design is wrong
CNC and machine shop	Machined metal and plastic parts to drawing tolerances	You need functional, load-bearing or heat-tolerant parts	Produce the drawings for you
Prototyping bureau	Multiple processes plus finishing, assembly and process advice	You are unsure which process suits the part	Own the engineering outcome
Electronics prototype house	Board fabrication, assembly, bring-up support	Your product is PCB-driven	Write your firmware
Product development firm	Requirements, design, engineering, prototypes and production handoff	You have a concept, not a file set	Compete with a printing bureau on part price

If you already have manufacturing-ready CAD and drawings, buy parts from a shop. If your files are a starting point rather than an answer, a product design and development firm is cheaper overall, because the alternative is paying to build the wrong part several times.

Screen a longlist before you ask for quotes

Send every shop on the longlist the same short questionnaire. The aim is to eliminate mismatches early, not to collect prices.

Screen	What to ask	Disqualifying answer
Process fit	Which process do you recommend for this part and why?	Whatever machine they happen to own
Materials	Can you deliver the resin, alloy or finish the design assumes?	A substitute proposed without discussing properties
Tolerances	What tolerance do you hold on features like this?	A number quoted with no measurement method
DFM feedback	Will you review the files before quoting?	Quote only, no engineering review
Path to production	What happens when this design moves to tooling?	No answer, or no relationships with production shops
IP handling	Do you sign an NDA and who owns the files?	Hesitation, or ownership retained by the shop

A shop that sends back three questions about your drawing before quoting is worth more than one that returns a price in an hour.

What a complete prototype quote contains

Process and material named exactly, including finish and colour.
Tolerance and inspection method, so "it fits" is measurable rather than an opinion.
Quantity breaks, because the second unit is usually far cheaper than the first.
Lead time from file approval, not from the date you sent the email.
Revision policy covering what happens when a change is needed mid-build.
Shipping, duties and post-processing, which frequently exceed the part price on small orders.

What prototypes cost and how long they take

Prototype type	Typical cost	Typical lead time	What it proves
Printed appearance model	$150 to $1,500	2 to 7 days	Size, proportion, grip and layout
Machined functional part	$300 to $5,000	1 to 3 weeks	Strength, tolerance and real material behaviour
Electronics prototype (PCB plus assembly)	$1,500 to $15,000	2 to 6 weeks	Circuit function, power draw, firmware bring-up
Working integrated prototype	$10,000 to $75,000	6 to 16 weeks	The whole product doing its job for a user
Bridge or pilot units	$15,000 to $150,000	8 to 20 weeks	Repeatability and readiness for tooling

Cost scales with the question you are asking. Do not buy a working integrated prototype to learn whether the handle is comfortable; that is a printed model and an afternoon of user testing. See our rapid prototyping guide for how to sequence those builds.

Red flags when evaluating prototype companies

No questions asked. A shop that quotes complex geometry without querying anything has not read the files.
Refusal to sign an NDA or vague answers about who owns the resulting files.
Prices far below the field. Usually a different material, a thinner wall or a hidden finishing charge.
No inspection report offered on tolerance-critical parts.
No production story. A partner who cannot describe the handoff to tooling leaves you restarting later.
Portfolio without context. Renders and photographs that no one will explain in a call.

Run a paid pilot before you commit

Give the two finalists the same small real job: one representative part, the same files, the same deadline. Compare the DFM comments, the communication, the inspection data and whether the delivered part matches the quote. That single test predicts the relationship better than any reference call.

Questions to ask on the first call

Which of your recent projects most resembles mine, and what went wrong on it?
Who will actually do the work — in-house staff or a subcontractor you manage?
What do you need from me to quote accurately, and what will you assume if it is missing?
How do you handle a part that fails inspection: rework, recut, or credit?
What is your standard tolerance, and what triggers an upcharge?
Who owns the CAD, the drawings and any design improvements you contribute?
How do you handle confidentiality before an NDA is signed?
What does a typical change request cost in time and money mid-build?

Comparing quotes on the same basis

Comparison line	What to normalize	Red flag
Scope	Parts only versus parts plus assembly	Assembly assumed but not priced
Material	Exact grade and finish	'Or equivalent' with no grade named
Tolerance	Stated default plus critical callouts	No tolerance statement at all
Iterations included	Number of revisions before recharge	Unlimited revisions promised verbally
Inspection	Dimensional report included or extra	No inspection deliverable
Lead time	Business days from PO or from file approval	Clock starts at an undefined moment
Payment terms	Deposit, milestone, delivery	Full payment before any deliverable

Key takeaways

Interview for judgment and communication, not just machine list and price.
Normalize quotes onto one scope before comparing numbers.
Settle IP ownership and confidentiality in writing before files leave your machine.
Run a small paid pilot before committing a full program to any shop.

Files, tolerances and what to send with an RFQ

The quality of a prototype quote is set by the package you send, not by the shop's goodwill. Incomplete packages produce padded prices because the shop is pricing unknowns, and they produce parts that are technically correct and functionally useless because nobody stated which dimensions mattered.

Item to send	Why the shop needs it	What happens without it
STEP or Parasolid geometry	Machine-readable geometry for CAM and printing	Mesh files force manual rebuild and added cost
2D drawing with critical dimensions	Tells the shop where tolerance matters	Everything held loose, or everything priced tight
Material and finish called out by grade	Cost and lead time depend on the exact grade	Substitution you find out about at delivery
Quantity and intended use	Drives process choice	A one-off priced as production, or vice versa
Inspection expectation	Defines what "good" means	No measurement data, disputes on arrival
Deadline and shipping method	Slots the job realistically	Quoted lead times that slip quietly

Tolerance discipline is where money is made or lost. As a rule of thumb, machined parts hold ±0.005 in comfortably and ±0.001 in at a premium; SLS and MJF nylon hold roughly ±0.3 percent of nominal; FDM should be treated as ±0.5 mm unless the shop proves otherwise. Call tight tolerances only on mating and sealing features, and let everything else run at standard.

Working with a prototype shop through the iterations

The first parts are rarely the last. What distinguishes a good relationship from a transactional one is how the second and third rounds go: whether the shop remembers your setup, keeps the fixture, and tells you when a design change will move the price.

Batch design changes into deliberate rounds instead of drip-feeding revisions; each restart costs setup time you pay for.
Ask for the DFM notes in writing, and apply them to the CAD rather than to the individual order.
Keep revision control strict. Name files with revision and date, and confirm the revision the shop is running before every build.
Request measurement data on critical dimensions from round two onward; it turns "it does not fit" into a specific number.
Pay promptly on small jobs. Prototype shops slot fast for reliable customers, and queue position is often worth more than a discount.

Expect three to five rounds on a typical hardware program: proof of concept, one or two functional iterations, an appearance-accurate build and a production-intent pilot. Related reading: rapid prototyping services and what prototypes cost.

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Frequently asked questions

What do prototype companies do?

Prototype companies turn a design into physical parts or working units so a team can test form, fit and function before investing in tooling. Some only fabricate from supplied files, while product development firms also create the design, engineering and drawings the prototype is built from.

How much does it cost to have a prototype made?

A printed appearance model typically runs $150 to $1,500, a machined functional part $300 to $5,000, and a working integrated prototype $10,000 to $75,000. The price is set by the question the prototype answers, not by its size.

Should I hire a machine shop or a product development firm?

Hire a shop when you already have manufacturing-ready CAD, drawings and tolerances. Hire a development firm when the design still has open questions, because a shop will build exactly what your files describe, including the mistakes.

How do I protect my idea when contacting prototype companies?

Use a mutual NDA before sharing files, confirm in writing that you own the deliverables and the CAD, and consider filing a provisional patent application before wide disclosure. Any credible shop signs an NDA without argument.

How long does a prototype take?

Printed parts arrive in two to seven days, machined parts in one to three weeks, and electronics prototypes in two to six weeks. A fully integrated working prototype usually takes six to sixteen weeks because it depends on several suppliers finishing in sequence.

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