A molder needs seven things to quote your part: a 3D solid model in STEP format, a 2D drawing with tolerances called out, a resin specification, estimated annual volume, order quantity, a finish and color spec, and a packaging requirement. Send all seven and you get a quote in 3 to 10 business days that lands within 10% of what you will pay. Send a photo and a paragraph and you get a range so wide it tells you nothing.
Three quotes on an identical package will still differ. The job is making sure they differ because of the molders, not because each one guessed at a different part.
The RFQ Package, Item by Item
1. 3D model.
Send a STEP file (AP214 or AP242). It is the universal solid format, every CAD system reads it, and it preserves the solid body rather than a mesh approximation. Parasolid (.x_t) and native SolidWorks files work if you have confirmed the molder runs the same system.
Do not send an STL. STL is a faceted mesh built for printing. A toolmaker cannot cut a cavity from a mesh without rebuilding the surfaces, and rebuilding introduces errors you will not find until first shots. IGES is legacy and often arrives with gaps in the surfaces.
One file per part. Send the assembly separately if the fit between parts matters, and it usually does.
2. 2D drawing.
The 3D model carries geometry. The drawing carries intent. A molder cannot infer from a solid model which dimensions matter, and every dimension is not equal.
The drawing should show:
- A datum scheme, so everyone measures from the same references
- Critical-to-function dimensions with their tolerances stated explicitly
- A default tolerance block for everything else, referencing a standard such as DIN 16742 or ISO 20457 with the tolerance grade you want
- Material and grade, by manufacturer and product name where it matters
- Surface finish callouts by SPI code or texture number
- Cosmetic surface classification: A surfaces (always visible, no defects), B surfaces (sometimes visible, minor defects allowed), C surfaces (never visible)
- Preferred parting line and any zones where a gate vestige is not acceptable
- Any regulatory requirement: UL 94 flame rating, food-contact compliance, RoHS
Molding holds about ±0.10 mm on a typical dimension without effort. If you tolerance every dimension at ±0.05 mm because it looked reasonable in CAD, expect the quote to carry a 20% to 40% penalty and expect a phone call.
3. Resin specification.
Name the resin, the grade, and the manufacturer if you have a reason to. “ABS” is not a specification. “ABS, Chi Mei PA-757 or equivalent, natural” is.
Resin choice changes tool steel, shrink allowance, cycle time, and press size. Changing it after the tool is cut can make the cavity unusable, because steel is cut oversize by the resin’s shrink factor and PP at 2.0% shrink and ABS at 0.5% are not interchangeable. The tradeoffs are laid out in choosing plastic materials for production.
If you are unsure, name two candidates and ask the molder to quote both. That is a fair request and a good molder will answer it.
4. Volume.
Give two numbers: estimated annual usage (EAU) and order quantity.
EAU sets the tool class and cavity count. Order quantity sets the setup amortization in the piece price. A part with a 50,000 EAU ordered in one annual release quotes differently than the same part ordered in monthly releases of 4,200, because the second one eats twelve setups a year.
Be honest about the number. Inflating EAU to get a better piece price gets you a tool sized for volume you will not hit and a molder who reprices the part when your releases come in low.
5. Color and finish.
Specify color by a physical master chip if the color matters, or by Pantone number if it is close enough. Add a delta E tolerance if you are matching to a brand standard; ΔE ≤ 1.0 is a tight commercial match and costs more to hold than ΔE ≤ 2.0.
Custom color matching costs $250 to $900 in lab work and carries a masterbatch minimum of 10 to 25 pounds. Molding in a stock natural or black resin and skipping the match is a legitimate way to save money on a first run.
6. Packaging.
Bulk in corrugated with layer pads is cheapest, at $0.02 to $0.12 per part. Individual bagging, thermoformed trays, or retail-ready packaging runs $0.10 to $0.40 and up. If you do not specify, the molder assumes bulk, and your quote is not comparable to one from a molder who assumed bagging.
7. Target price.
Share your target piece price. Do not share your tooling budget.
Target price is useful information: it tells the molder whether to quote a two-cavity or four-cavity approach and whether your design is anywhere near feasible at your price point. Tooling budget is an anchor that only moves the quote one direction.
What to Demand Back
Most inventors receive a quote with two numbers on it and no way to interpret them. Ask for these line items in writing, on every quote:
| Line item | Why it matters |
|---|---|
| Tool class (SPI 101 to 105) | Determines rated life. A 3x price gap usually turns out to be a class gap. |
| Cavity count | Sets piece price and tool cost together. |
| Cavity and core steel spec | P20, H13, NAK80, 420 SS, or aluminum. Sets tool life and abrasion resistance. |
| Runner type | Cold, hot tip, or valve gate manifold. |
| Number of tool actions | Slides and lifters, itemized. |
| Estimated cycle time | Lets you sanity check the machine time in the piece price. |
| Press tonnage | Confirms they have the right machine for the part. |
| Shot weight | Part plus runner. Lets you check the material cost. |
| Scrap allowance | 1% to 3% is normal. Higher means they see a difficult part. |
| Sampling rounds included | T1, T2, T3. Most quotes include two. Extra rounds cost $800 to $3,500. |
| Tooling lead time and sampling lead time | Separately, not combined. |
| First article inspection cost | $600 to $4,000 depending on dimension count. |
| Tool ownership terms | The one people skip. |
| Spare insert pricing | Get it now, not during a production emergency. |
| Price breaks by quantity | 1,000 / 5,000 / 25,000 / 100,000. |
The tool ownership line deserves its own conversation. A quote that says “tooling included” or “no tooling charge” almost always means the molder holds title and recovers the tool through the piece price, which locks you to that shop. Who owns the mold and the clause to insist on walks through the three ownership structures and what each one costs you if you ever want to leave.
Comparing Three Quotes Without Fooling Yourself
Build a single spreadsheet with one row per line item and one column per molder. Then normalize.
Say you get these back on the same 42-gram ABS housing:
| Molder A | Molder B | Molder C | |
|---|---|---|---|
| Tooling | $19,500 | $31,000 | $12,800 |
| Piece price at 25,000 | $0.71 | $0.58 | $0.94 |
| Cavities | 1 | 2 | 1 |
| Steel | P20 | H13 | Aluminum |
| Rated life | 250,000 | 1,000,000 | 40,000 |
| Lead time | 11 weeks | 16 weeks | 5 weeks |
| Tool ownership | Customer | Customer | Molder |
Now do the total-cost math at your real volume. At 25,000 units a year over three years, so 75,000 units:
- A: $19,500 + (75,000 × $0.71) = $72,750, and the tool has life left
- B: $31,000 + (75,000 × $0.58) = $74,500, with 925,000 shots of unused life you paid for
- C: $12,800 + (75,000 × $0.94) = $83,300, and you will need two more tools, and you do not own any of them
C looked cheapest and finished last. B looked most expensive and is competitive, but only if volume grows. A is the right tool for the stated volume. That comparison is impossible without the line items, which is why you ask for them.
Red Flags in a Molding Quote
A quote that arrives in under 24 hours with no questions. A molder who reviews a real part finds something to ask about: a wall transition, a gate location, an undercut you did not flag. Silence means nobody opened the file.
No tool class or steel spec stated. You cannot compare what is not defined.
“Free tooling.” The tool is never free. It is amortized into the piece price at $0.20 to $0.60 per part, and the balance comes due if you leave early or fall short of committed volume.
A price that is 40% below the other two. Either they misread the part, they are quoting a lower tool class, or they are buying the job and will reprice after the tool is cut. Ask which.
Reluctance to sign an NDA. A shop that will not sign a mutual NDA before receiving your CAD is telling you something about how they handle other people’s files.
No mention of DFM feedback. Good molders send back a marked-up model showing draft problems, thick sections, and undercuts. That feedback is worth more than the quote. If nobody has reviewed the part for manufacturability before the RFQ went out, their markup will be long.
Protect the Files Before You Send Them
An RFQ means your complete geometry sits on three or four servers belonging to companies you have not met. Two protections apply before you hit send.
First, file a provisional patent application. The USPTO’s guidance on provisional applications covers what one is and what it does: it establishes a filing date and gives you 12 months to convert, at a small entity fee of $130 to $325. Filing before disclosure is the sequence that keeps your options open.
Second, know what you are protecting. A $399 patent search tells you whether the mechanism is clear before you spend anything on tooling. The USPTO’s patent basics explains what a search does and does not settle.
Then send a mutual NDA with the RFQ. Most contract manufacturers sign one without argument, and the ones who hesitate have told you what you needed to know.
How Many Molders to Quote
Three to five. Fewer than three and you have no baseline. More than five and you are spending weeks managing an RFQ process for a spread that will not widen.
Mix the pool: one large shop, two mid-size, one specialist in your part type. If you are considering offshore, quote at least one domestic and one overseas so you can run the landed cost comparison in domestic vs overseas manufacturing rather than guessing at it. How to build that shortlist in the first place is covered in finding a manufacturing partner.
Expect to spend 8 to 16 hours assembling the package and 3 to 6 weeks running the process to a decision. That is cheap next to a $30,000 tool cut to the wrong spec, and it is the step where Enhance’s manufacturing sourcing work does most of its work for inventors who have never run an RFQ. If you are still assembling the rest of your budget, the answers to the questions inventors ask most puts tooling next to the other costs coming at you.
FAQ
How long does an injection molding quote take?
Three to ten business days for a straightforward part with a complete RFQ package. Two to three weeks for a large or complex part, a part with multiple actions, or a program with several parts quoted together. If a quote comes back in a few hours, ask what they reviewed.
Do I need a 2D drawing if I have a 3D model?
Yes. The model says what the part is. The drawing says which dimensions have to be right, how tight, measured from where, and what the part has to look like. Without it, the molder picks tolerances, and you find out which ones they picked at first article inspection.
Will molders quote a part with no drawing at all?
Some will, with a default tolerance assumption and language that protects them. That quote is an estimate. Treat it as a budgetary number for a business plan, not as a price you can hold anyone to.
Should I tell the molder my target price?
Yes for piece price, no for tooling budget. Target piece price helps them propose the right cavitation and flag whether your design is feasible at that number. Tooling budget only anchors the tooling quote upward.
What is a T1 sample and how many rounds should I expect?
T1 is the first shot off the new tool. Almost no tool produces acceptable parts on T1. Expect T1, T2, and often T3 before first article approval, spread over 2 to 5 weeks. Confirm how many rounds the quote includes, because each additional round runs $800 to $3,500 and adds a week. The piece price and tooling numbers behind all of this are broken out in what injection molding costs.