What should I include in a quote request so my first sample fits?

A quote request that leads to a first sample that fits names the critical dimensions, not only the part. Send a drawing or 3D file with tolerances marked, the material grade and hardness, the color and finish standard, your target volume and the packaging. In our experience, tolerances are what new buyers most often forget.

What should a quote request include?

Six items cover most of what a manufacturer needs to quote a part and judge whether it can be made as drawn. You do not need all of them on day one, but each one you add makes the first number closer to the final one.

What to send	What it should say	Why it matters
Drawing or 3D file	The part as you want it made, ideally a drawing and a 3D file together	The quote and the design review both start here
Critical dimensions and tolerances	The features that must fit something else, marked on the drawing, with the tolerance each one needs	These decide whether the first sample fits
Material grade and hardness	The material by grade, and hardness where it matters, for example Shore A for a soft material. If you do not know the grade, describe the job the part has to do	Material changes the tool, the shrink and how two materials bond
Color and finish standard	The color reference, and the surface finish you expect, such as matte, gloss or textured	Finish is judged against a standard, and it needs one written down
Target volume	Expected yearly volume and your target timeline	It shapes how the tool is built
Packaging	How the parts should be packed and labeled, if it matters to you	Packing follows molding, so it is better decided early

Why do I need to mark tolerances and critical dimensions?

A drawing without marked tolerances tells the factory what the part looks like, but not which dimensions matter. A tolerance is the amount a dimension is allowed to vary. Without one, every dimension looks equally important, and the ones that really matter to you get no extra care.

In our experience, this is the item new buyers most often forget to specify. It is easy to do, because the part looks right on screen. The trouble shows up later, when the molded part has to fit a mating part, a seal or a housing, and a small difference turns into a part that does not fit.

A short list helps. Pick the features that touch something else, mark them, and write the tolerance beside each one. If the part has to fit another part from a different supplier, send that part’s drawing too.

Why do first samples fail, and how many rounds should I expect?

The most common reason a first sample fails is fit and dimensions: parts that do not fit together, or that are out of tolerance. That is why the marked tolerances above matter more than any other detail in the request.

For an overmolded or two-shot part, a customer typically goes through 2 to 3 sample rounds before signing off, in our experience across projects at our Shenzhen plant since 1996. That is an estimate, and every part is different. Other parts can take more or fewer. Your rounds are confirmed when you approve the samples.

A clear request does not remove sample rounds, but it removes the avoidable ones. If the fit was never specified, a round gets spent finding out what it should have been. Our page on what a first production run needs explains how samples and approval work.

What if I am not sure about the material or the finish?

Say what the part has to do, and we will suggest a material. A request that says “a soft grip that stays bonded to a hard handle, used outdoors” is more useful than a guess at a grade.

This matters most when the part uses more than one material. A part that bonds badly is cheaper to fix in design review than after the mold is cut, so tell us early if two or more materials have to hold together. The design review checks shrink and bonding on every project. See why multi-material parts fail for what that review looks for.

What happens after I send the request?

An engineer reads it. If the part is a fit, you get questions about material, tolerance and finish. If it is not a fit, we say so and explain why. The design review comes before any steel is cut.

You pay for the mold and you own it, and the useful early questions are what the tooling costs and whether you can fund it. Our Tooling & Minimums page covers that. If you are also choosing between suppliers, our checklist for choosing a contract manufacturer covers what to check on the factory side.

When you are ready, get a quote and attach the drawing or file, with the critical dimensions and tolerances marked.