STEP vs STL vs IGES for Custom Silicone Molds

Your CAD lands as STEP, STL, or a 1990s IGES export — and the quote clock starts. Wrong format does not kill the job, but it does burn a day when we have to rebuild solids before DFM. This page is the format call for soft silicone tooling at RUUIPON (Shenzhen since 2018, MOQ 20). For the full RFQ pack (units, draft, logo depth), use the CAD file checklist.

What Shows Up in the RFQ Inbox

Brand buyers send phone photos, Etsy meshes, SolidWorks STEP, and old IGES from a previous factory. We can start from any of them. The decision is which path locks cavity grams without a second modeling deposit.

• STEP / STP — solids we can measure, draft, and revise.
• STL — triangles. Fine for organic shapes if watertight and units are stated.
• IGES — still arrives from older CAD. Workable; we often re-export to STEP before tooling.

Format Decision Table

Format	Best for	Watch-outs
STEP / STP	Logo bars, multi-cavity trays, DFM edits	Name the units (mm)
STL	Organic characters, scanned masters	Scale, holes, non-manifold edges
IGES	Legacy exports	Surface gaps; we may rebuild
Photos only	First brief	Needs scale object; CAD path may use ~$50 drawing deposit

When STEP Wins

If you already have a solid model, send STEP. We check draft, undercuts, and logo depth in mm before the master is cut. Revisions stay cheap while the file is a solid — after a mesh remesh, every logo tweak costs more time.

When STL Is Enough

Character candy, scanned resin masters, and sculpted wax often only exist as STL. Send it if: (1) watertight, (2) scale in mm is written in the email, (3) you accept we may thicken walls for soft-tool demold. A 0.2 mm paper-thin wall that looks fine in a render will tear on demold 3.

Legacy IGES / STP

IGES still works. Tell us the source CAD and units. We often convert to STEP for the revision loop so you and we are looking at the same solid.

Only Photos — No CAD Yet

That is a normal first email. Start on custom silicone mold from photos: top + side + ruler, pour chemistry, target grams. When we must model cavities, the ~$50 drawing deposit path may apply — confirmed on the quote. Prototype commonly 3–7 business days after CAD lock.

FAQ

Which format for a first tool?
STEP if you have it. Watertight STL with units stated is fine for organic shapes.

Is OBJ or GLB OK?
We can look. Production DFM still wants STEP or a dimensioned STL.

Does a better file lower MOQ?
No. MOQ stays 20 mold pieces per design after sample approval.

How fast is the quote?
Complete RFQs typically get a reply within about 24 hours.

Next: attach STEP/STL + pour + qty — request a quote or WhatsApp +86 135 3006 2969. Manufacturer hub: custom silicone mold manufacturer.