A prototype RFQ that arrives with a STEP file and a one-line email produces a quote that is accurate only by luck. The shop must guess which faces are functional, whether the finish matters, what quantity the price should cover, and whether the threads are coated or bare. Each guess has a cost direction: a tighter tolerance than needed raises the price, a missing finish note lowers it until the first sample arrives wrong, and an unclear quantity makes the unit price meaningless. The file package sent with an RFQ is the specification the shop quotes against, and a complete package is the fastest way to turn a quote into a usable comparison.
The file set that lets a shop quote accurately
A useful RFQ file set has four parts: a neutral CAD format such as STEP, a drawing or a dimensioned PDF, a specification sheet or notes, and a clear quantity-and-schedule line. STEP carries the geometry; the drawing carries the tolerances and the callouts; the notes carry the intent that neither file can show; and the quantity makes the price meaningful. Formats matter: STEP is the common interchange for machining quotes, while STL serves printing quotes and the drawing should match the CAD revision exactly. Sending an old drawing with a new model forces the shop to choose which file is true, and the quote inherits the confusion.
Name the file with the revision and keep the model, the drawing, and the notes on the same revision. The RFQ basics guide explains the request itself; the package below is what makes it complete.
Drawing notes that change the quote: tolerances, finishes, and threads
The notes on the drawing are where the price is really set. Mark the critical tolerances and leave the rest to a general block; a drawing that tightens every dimension pays for precision the function does not use. State the finish on the functional surfaces and note whether the finish is measured before or after coating, because a plated or anodized thread changes the fit. Call out threads with the class and the coating basis, and mark the surfaces that must stay bare. Every note that removes a shop’s guess reduces both the price and the risk of a first article that misses the intent.
For a prototype, note which features are functional and which are placeholders. A shop that knows the boss is a test feature will quote it differently from one that assumes it carries a production load — and the sample will be inspected against the right criteria.
Quantity and forecast: what to state and what to hold back
The quote depends on the quantity, so state the prototype quantity and, where it matters, the expected production volume. The per-part price at ten parts is not the price at a thousand, and the tooling or setup decision changes with the forecast. Hold back nothing that affects the quote, but do not overcommit: if the production volume is uncertain, say so, and ask for the price at the prototype quantity plus an indication of how the unit price scales. A shop that knows the forecast can choose the process that serves the full program; one that quotes a single unknown quantity will price for the worst case.
Lead time belongs in the same line: when the parts are needed, whether the quantity can be split, and which milestones matter. A schedule that names the dates lets the shop sequence the work; one that says “ASAP” produces a conservative lead time that protects the shop, not the program.
Special inputs for moving parts, inserts, and assemblies
Moving parts and assemblies need more than geometry. If the prototype has a press fit, name the mating part and the fit class; if it carries inserts, state the insert type and the installation method; if it is part of an assembly, include the mating geometry or the assembly drawing. The shop cannot design the fit or the insert pocket from a single part file, and the RFQ that includes the context produces a part that actually assembles. For a prototype that will be tested, include the test condition: the load, the temperature, or the environment, so the material and the finish are chosen for the test rather than for the bench.
Special notes also cover the documentation: whether the part needs a material certificate, an inspection report, or a first-article check, and who will measure the critical features. A prototype that will be used in a regulated or customer-facing test needs the document chain from the first order, not from the production order.
A five-minute RFQ self-check before send
Before the RFQ leaves, run a short checklist. Confirm the CAD and the drawing match the same revision; mark the critical tolerances and the functional surfaces; state the finish and the coating basis; include the quantity, the schedule, and the forecast; name the inserts, the mating parts, and the test conditions; and list the documents the parts must carry. Each unchecked box is a guess the shop will make, and each guess is a future change order. The five minutes spent on the checklist are repaid in the first quote that needs no revision and the first part that arrives right.
What a complete package changes in practice
A comparison of two RFQ packages shows the difference in action. Supplier A receives a STEP file, a drawing, and a note that the part is a prototype bracket, with the critical hole pattern marked and the finish described on visible faces. Supplier B receives the same STEP file with a one-line email asking for a quote. Supplier A asks whether the holes need a positional tolerance relative to the datum face, confirms the finish thickness and masking, and quotes a price that includes the inspection report on the hole pattern. Supplier B quotes the geometry as interpreted from the model, with no finish line and no inspection, at a price that looks lower. The buyer who compares the two quotes without the notes is comparing a complete scope against an assumed one, and the difference shows up at the first sample: Supplier A’s part passes, and Supplier B’s part arrives with the wrong finish and an unverified hole pattern. The RFQ package did not just change the price; it changed which part was quoted. That is the real function of the file set and the notes: they define the scope so the quote, the sample, and the inspection all refer to the same requirement.
The second benefit of a complete package is speed. Every missing note generates a question, and every question waits for a reply across time zones and schedules. A package that answers the obvious questions in advance — material, finish, quantity, schedule, and critical features — lets the shop quote immediately and start the engineering review that a prototype needs: the DFM check that catches a tolerance that cannot be held, a finish that will not survive the test, or a thread that needs an insert. That review is where the prototype program saves its real time and money, and it happens only when the shop understands the intent. The five-minute self-check is the habit that produces this result, and it scales: the same package discipline that works for one prototype works for a hundred. A program that treats the RFQ as the start of the engineering conversation gets better quotes, better samples, and fewer change orders.
The package that scales is the one written once and reused. A company that quotes the same housing family repeatedly builds a library of RFQ templates: the drawing notes, the finish callouts, the quantity logic, and the documentation list are defined once and adapted per part. The library removes the start-from-scratch cost from every quote request, and it gives the shop a consistent language across programs. The discipline also builds the supplier relationship: a shop that receives complete packages learns the buyer’s conventions, answers faster, and flags risks earlier, because it is not spending the quote cycle decoding the request. The five-minute self-check becomes a habit that the whole team follows, and the habit is what protects the program when a new engineer or a new supplier joins mid-project. A prototype RFQ is a small document with a large effect, and the effect compounds when the package discipline is part of the product development process rather than a favor done for the shop.
The habit that keeps the package complete is a template with the checklist built in. Create a one-page RFQ cover sheet with fields for the revision, the critical features, the finish, the quantity, and the documents, and make it the required first page of every quote request. The template removes the dependence on memory and gives the shop a familiar format, and the revision history on the cover sheet protects both sides when a file changes. This is the practical answer to the question of how the discipline survives a busy team: it is built into the process, not carried in anyone’s head.
If you are preparing a prototype RFQ and want the package reviewed before it goes out, the 6CProto rapid prototyping team can review the file set, the notes, and the quantity basis together — the review is faster before the quote than after the first bad sample.