Many startup founders, hardware designers and overseas buyers reach out with product photos or screenshots and ask for a mold & part quotation. On the surface, the shape looks clear enough. But photos are only pixels — they carry no dimensional data, material properties, tolerance values or production‑volume context.
Industry internal data shows: quotations built purely from photos carry 35‑65% risk of major price deviation versus real‑project cost. Suppliers must make dozens of unconfirmed assumptions about wall thickness, undercuts, surface texture, resin grade and annual output. When real samples or CAD files arrive later, the final price can jump 30% or more, causing budget shock and project delays.
Photos can work as reference for general concept discussion. They are never sufficient for formal, binding quotation.
A photograph shows outer visual shape, but cannot deliver these core technical inputs that directly drive mold cost and per‑part price.
|
Parameter |
Information you cannot get from photos |
Typical cost impact if guessed incorrectly |
|---|---|---|
|
Exact dimensions & wall‑thickness |
No scale; invisible internal ribs, bosses, hidden undercuts, wall‑thickness ratios |
15‑35% higher tooling cost if hidden side‑actions / lifters are required |
|
Plastic material grade |
Cannot distinguish ABS, PP‑GF30, PC‑FR, TPE over‑mold from appearance; shrinkage rates differ widely |
8‑25% difference in per‑part cost; also changes required mold steel hardness |
|
Tolerance requirements |
No visibility of mating critical dimensions, GD&T requirements |
12‑22% mold cost increase for overly tight tolerances |
|
Surface finish / texture |
Cannot tell SPI‑A1 polish, VDI texture, matte blast or cosmetic A‑surface standards |
10‑20% tooling difference between high‑gloss polish vs standard blast finish |
|
Expected production volume |
No clue of monthly / annual quantity to decide cavity count, mold steel grade (P20 / H13) |
20‑40% swing between low‑volume aluminum tool vs high‑volume hardened‑steel multi‑cavity mold |
Even high‑resolution product photos cannot reveal internal geometry. Snapshots cannot measure draft angles, fillet radii or deep internal grooves. All those features decide how complex your injection mold will be.
Below checklist splits requirements into mandatory items and helpful supporting documents. Providing this complete package enables suppliers to return accurate pricing within 24‑48 working hours.
|
Item |
Specification & Notes |
|---|---|
|
3D CAD File |
Preferred format: STEP (.stp /.step). IGES / Parasolid acceptable. STL only for visual reference, not for quoting production molds |
|
2D engineering drawing |
Mark critical dimensions, tolerance bands, surface‑finish codes, cosmetic zones. General default tolerance ±0.05 mm without drawing. |
|
Material specification |
Resin family + grade; additives: glass‑fiber %, UV‑stabilized, flame retardant, food‑contact compliance. If unknown, state target end‑use environment. |
|
Target annual / batch production volume |
Determines cavity quantity, mold steel selection, hot‑runner vs cold‑runner design. |
|
Surface‑finish requirement |
SPI grade / VDI texture number; mark which areas are cosmetic A‑surfaces. |
Highly Recommended Supporting Inputs
Physical sample: Best option if CAD files are incomplete. Makers can measure wall‑thickness, inspect hidden undercuts and reverse‑engineer key features.
Functional description: How this part will be used, assembly conditions, working temperature, chemical exposure.
Special processes: Insert molding, over‑molding, post‑mold assembly, printing / painting requirements.
Target timeline: Expected tool‑kick‑off date, desired first‑sample timeline.
Practical note: If you cannot share native CAD due to confidentiality, sending a physical sample still delivers 80%+ of technical data needed for realistic budget estimation. Photos alone deliver less than 30% of required technical information.
A hardware startup sent only product photos requesting a quotation for a consumer housing. Based purely on outer visuals, the supplier estimated a single‑cavity P20‑steel mold. When the physical sample arrived later, engineers discovered 4 internal undercuts requiring lifter mechanisms plus 2 mm deep VDI‑27 texture across all outer surfaces.
Final tooling price ended up 38 % higher than the initial photo‑based rough estimate, and project lead‑time extended by two weeks. This is a very common scenario across custom plastic projects.
Use photos for concept discussion only, not for formal RFQ bidding.
Send STEP 3D files + 2D drawing whenever possible; physical samples are an excellent fallback option.
Clearly state material grade, volume expectation and cosmetic requirements. Avoid forcing manufacturers to guess critical parameters. Guesses almost always work against your project budget.
Next Step for your project: Prepare your RFQ package with 3D files or physical samples. At JBRplas, our engineering team can run a free pre‑quote DFM review and flag potential cost‑driving geometry before you receive formal pricing.
