Start with the answer. A set of exterior 3D files bought from an appearance-styling studio usually cannot go straight into a mould. What arrives is a surface model: the outside is resolved, the inside is empty. Before a toolmaker will quote against it, three pieces of structural information have to be added — the draft angle along the release direction, the ratio between main wall thickness and rib thickness, and a decision on how the undercuts at snaps and screw bosses get handled. With those three in place the file is manufacturable. Without them the mould shop sends it back, and the drawing gets rebuilt by somebody who never saw the original intent.
The short version: we run the same three checks whenever a file lands on our desk — draft, wall-to-rib ratio, undercut direction. All three pass and the drawing is worth taking to a mould shop. On price, appearance only runs 5,000-12,000 CNY, appearance with structure 15,000-40,000 CNY, and the full scope 30,000-80,000 CNY. The difference between those bands is almost entirely about whether the file can enter a mould.
The cost of getting this wrong is calendar time, not money. A missing draft is an afternoon's correction while the model is still open, and a fortnight's correction after T0, because the cosmetic surface has to be rebuilt and every review that signed off the original line has to happen a second time. We have watched a project lose two weeks to a draft angle that came up short on one side wall.
Three checks before anyone talks about tooling
Draft, wall-to-rib ratio, undercut direction. Those are the places a toolmaker flips to first, and the places an appearance team most often leaves out. Most of the files we send back in our own internal review fail on one of the three.
Draft follows the release direction. On a polished surface we work to 1 degree. On a textured surface the angle climbs with the depth of the grain, and heavy texture gets 3 degrees or more. If the angle is short, the mould shop will not quietly fix it — they call and ask you to add it, and once you add it and pull the surface, the waistline you spent two weeks tuning goes crooked. Re-cutting an A-surface means the form review before it was mostly wasted.
Rib thickness is derived from the main wall. We run ribs at 0.5 to 0.6 of the main wall thickness. The last power bank shell had a 2.0 mm wall, and at T0 the part came out with 0.3 mm of sink. The first assumption was unstable injection pressure; then we measured the tool and found the ribs had been drawn at 0.8 of the wall. Local mass piled up and the sink was inevitable. That class of defect does not respond to machine settings. You change the drawing or you live with it.
Undercuts decide the tool. Which side the undercut faces determines whether the mould needs a slider or a lifter. The same battery-door catch, buried deep inside the housing or opened out to the side, can move the tool cost by a whole band. If an appearance studio draws the catch for looks alone, the toolmaker will redraw it for feasibility, and that extra loop costs calendar time nobody gets back.
What the quote covers, and where the gap actually sits
The gap is in deliverables, not in drawing hours. Appearance only hands over renders plus the exterior 3D, with the inside left empty. The structure tier hands over a complete assembly model that can go into a mould, plus a DFM review. The full scope adds prototype validation, CMF samples and trial-shot attendance.
| Appearance only | Appearance + structure | Full scope | |
|---|---|---|---|
| Tooling-ready 3D | No | Yes | Yes |
| DFM review | No | Yes | Yes |
| Prototype and CMF samples | No | Quoted separately | Included |
| Trial-shot attendance | No | Quoted separately | Included |
| Price band (CNY) | 5,000-12,000 | 15,000-40,000 | 30,000-80,000 |
A mould shop handed an appearance-only file has two routes: tell the client to go and find a structural engineer, or fill the inside in from experience. What gets filled in that way — whether the parts fit, whether the button feels right, whether the assembly sequence works — has no owner. We have picked up a few of these half-finished files. The hard part is never the redraw. The hard part is reconstructing why the previous person decided that one particular wall should be thick.
The decision rule, in one line: if the product is a new category and the internal stack-up is not settled, take the structure tier. If it is a mature platform being re-skinned and the main structure and assembly relationships stay as they are, appearance only is enough. The only test that matters is who is accountable for "it fits".
Three questions that reveal whether a studio knows manufacturing
Ask these and most of the field drops out. First: once the structural drawings are finished, will you sit down with the toolmaker for a DFM review, and will the comments end up on the drawing? Second: do you attend T0? Third, the one that cannot be rehearsed — on your last product, what changed between T0 and T1?
There is no way to prepare for the third. Someone who has actually followed a tool will tell you a catch snapped, an injection gate left a mark, a decorative part sat with an uneven gap after assembly — and they will remember how many revisions it took and what the fix was. Someone who has only drawn will generalise. That is the tell.
Location is the other signal. Hezi sits in Wanjiang, Dongguan, and a two-hour drive covers most of the injection moulders and surface-finishing shops in the Pearl River Delta. A revised prototype can be in hand the same day, and when a trial shot throws up a problem we can be on site. Working at a distance is not impossible — plenty of our 200+ enterprise clients are outside the region — but it runs on fixed review gates and live video from the floor rather than on photos sent through a chat app, and the travel time has to be costed in.
When an appearance-only studio is the wrong hire
Three cases: a new product whose internal stack-up is still open; a category with a battery in it, or one that has to clear a safety certification; and a multi-part assembly with more than five components. Force any of those through the appearance tier and the money you save comes back during trial shots as tool modifications, usually an order of magnitude larger than the design fee.
The reverse is also true, and it is worth saying because clients over-buy. A model already in production that needs a new colourway, a label, or a different panel texture — main structure untouched — is well served by the appearance tier. Part of the 65% of our business that is repeat clients is exactly this: fast drawings, cheap validation.
| Your situation | Recommended tier | Why |
|---|---|---|
| Mature platform, exterior change only | Appearance only | Internal structure untouched, no new tooling drawing needed |
| New category, stack-up still open | Appearance + structure | Assembly relationships have to be set alongside the form |
| Prototyping, trial shots, multiple CMF rounds | Full scope | Many handover points between design and production |
FAQ: common questions about appearance-styling studios
Q: How do appearance-styling studios usually charge?
A: By tier: appearance only 5,000-12,000 CNY, appearance with structure 15,000-40,000 CNY, full scope 30,000-80,000 CNY.
The difference tracks whether the deliverables include a tooling drawing, a DFM review, prototype validation and trial-shot attendance. It does not track how many renders were produced.
Q: If a studio only does appearance, can the files go straight to tooling?
A: Usually not. An exterior 3D is a surface model — it carries no wall thickness, no ribs, no snap details.
Faced with that file, a mould shop either sends the client off to find a structural engineer or fills the inside in from experience. Whether the result assembles is not the design studio's responsibility.
Q: How do you verify that a studio has production experience?
A: Ask them to describe what changed between T0 and T1 on a recent product. If they cannot give details, they probably have not followed a tool.
Someone who has will name the catch that snapped, the gate that left a mark, how many revisions it took and what the final fix was. That question cannot be prepared for in advance.
Q: Does working with a studio in another city cause problems?
A: It can work, but it runs on fixed review gates and live video, not on photos sent through a chat app.
Many of Hezi's 200+ enterprise clients are outside the Pearl River Delta. What has to be budgeted is travel time: if a trial shot goes wrong, someone in Dongguan can be there the same day; from a distance it is the next day.
Q: The design is finished and the mould shop says it cannot be made. Whose responsibility is that?
A: Look at whether the contract includes a DFM review. Without that line item, handing over the drawing counts as delivery complete.
Before signing, put "one DFM review with the toolmaker, with the comments applied to the drawing" into the scope of work. That is worth far more than an argument afterwards.
Written by the Hezi Industrial Design team, from project practice in Dongguan. Hezi does appearance design, structural design and CMF as one service — 320+ products in production. Website: www.hezidesign.com
