Free browser tool for insole makers · no sign-up required

Resize, widen, and trim your insole STL.Keep the geometry you need. Print the fit you want.

Open a printable STL or mesh OBJ, split paired insoles, correct inch or centimetre units, set exact dimensions, add controlled width, or trim a full-length insole to 3/4 length. Your model stays in your browser.

Free STL exports No account required Local processing
A bright TPU insole being 3D printed on a desktop FDM printer
INSOLE PRESETSWide +2 / +4 / +6 · 3/4 cut
ANY PRINTABLE MODELScale · rotate · split STL/OBJ

Step 1 Ergono3D pair splitter

Separate a pair into two models.

Upload one STL or OBJ containing two disconnected insoles. Each model stays unchanged—no cutting plane and no new cap.

Best for two similar separate models · stays on this device

PAIR STL → TWO MODELS Keep each insole whole.

Disconnected bodies are separated directly, so the original surfaces and details stay intact.

Step 2 Scale / Wide / Cut

Edit one model below.

Choose either separated model above, or open any single STL or OBJ here. Wide and 3/4 remain tuned for insoles.

Demo model ready
Drag to orbit · scroll to zoom
Length—
Width—
Height—
Triangles—
ChangeOriginal
Binary STL · millimetres

From downloaded model to slicer

How to resize or cut an insole STL for 3D printing.

Use only the operations your model needs. The free workbench keeps the original available to reset, then exports a fresh binary STL in millimetres.

  1. 01

    Open one model—or separate a pair

    Use the pair splitter when one file contains two disconnected insoles. Otherwise, open a single STL or OBJ directly in the workbench.

  2. 02

    Confirm units and finished size

    STL files do not store units. Convert inches or centimetres to millimetres, then enter a target length, width or height. Keep the ratio locked for proportional resizing.

  3. 03

    Adjust width or choose a trim

    Use Wide for a progressive forefoot-focused change, the 3/4 preset for a quick heel-side trim, or position a custom cut plane for another result.

  4. 04

    Export and inspect before printing

    Download the edited STL, open it in your slicer and check orientation, scale and mesh integrity. Then use the TPU insole printing guide for print setup.

Ergono3D Wide

Widen an insole STL without scaling every section equally.

Uniform width scaling expands the heel, arch, forefoot and toe by the same ratio. Wide applies a progressive change while preserving the model's length and height.

/ 01Read

Detect heel and toe

The tool finds the insole's long axis, narrower heel and local centreline from the mesh geometry.

/ 02Expand

Blend the width change

The heel changes least. Added width grows through the arch, reaches its maximum at the forefoot and eases toward the toe.

/ 03Preserve

Keep length and thickness

The centreline, overall length and vertical profile stay unchanged while the printable mesh remains connected.

Six common model fixes

Prepare an insole STL without going back to CAD.

Each operation is optional. Start with your own model, make the smallest useful change and export without an account or watermark.

A + B

Split a paired insole file

Separate two disconnected insole bodies and download each original mesh as its own STL.

254.0 mm

Resize to an exact dimension

Enter the finished length, width or height, with proportional scaling on or off.

in → mm

Correct an STL unit mismatch

Convert models made in inches, centimetres or metres to the millimetres most slicers expect.

+2 / +4 / +6

Make an insole progressively wider

Add the most width around the forefoot, with a smaller blended change toward the heel and toe.

¾

Make a three-quarter insole

Keep the heel-side 75%, remove the toe-side 25% and cap the new edge for export.

A / B

Make a custom planar cut

Move, rotate and tilt the cut plane, then keep one closed piece or download both STL parts.

Keep making

Useful next steps for a printable insole project.

The workbench edits an existing mesh. These focused Ergono3D resources cover the steps before and after the STL.

01 · DESIGN

Need a starting insole STL?

Build configurable insole geometry in Ergono3D, then use this free workbench whenever you need a quick resize, Wide version or trim.

Explore the insole STL generator
02 · PRINT

Dial in the TPU print.

Review orientation, supports, walls, infill and practical TPU settings before sending the edited model to your printer.

Read the TPU printing guide
03 · ITERATE

Follow the complete DIY workflow.

Move from measuring and choosing a model through slicing, printing and checking the result in footwear.

Read the DIY insole guide

New to the whole process? See the Ergono3D workflow for makers for a broader overview.

Private by design

Your model stays yours.

Files are read into browser memory and processed with WebGL on your device. There is no model upload, account, watermark or server-side copy.

Before you export

A few useful details.

/ Q-01Which files can I open?
Binary or ASCII STL and mesh-based OBJ files. Materials and textures are ignored because the output is a printable binary STL. For reliable browser performance, keep files under 100 MB and roughly one million triangles.
/ Q-02Can I resize an insole STL to an exact length?
Yes. Enter the finished length in millimetres with Lock ratio on to resize the whole model proportionally. Turn Lock ratio off only when you intentionally want to change one axis independently.
/ Q-03How do I convert an STL from inches or centimetres to millimetres?
Choose the original unit under Source unit. The tool converts inches, centimetres or metres to millimetres and exports a binary STL ready for a millimetre-based slicer workflow.
/ Q-04How is Wide different from scaling width?
Width scaling multiplies every point by one constant, so the heel and arch grow just as aggressively as the forefoot. Ergono3D Wide adds a measured amount around the forefoot and blends a smaller addition toward the heel and toe while preserving each section's centre.
/ Q-05Where does the 3/4 preset cut?
The tool compares both ends, identifies the narrower end as the heel, keeps the heel-side 75% and removes the toe-side 25%. If it detects your model backwards, use Swap heel / toe. For a different trim line, use the custom position and angle controls.
/ Q-06Will a cut always be watertight?
The cutter closes clean boundary loops with a planar cap. A manifold, watertight source usually produces a watertight result. Self-intersections, open edges or extremely thin triangles in the source can also appear in the result, so run your slicer's mesh check before printing.

Ready to design, not just edit?

Create the insole geometry in Ergono3D.

Start with a configurable, print-ready insole and control its dimensions, arch, heel cup, posting, flanges and lattice. This Scale & Cut workbench stays free for your Ergono3D exports—and other compatible STL or OBJ files.

Create an insole free →Explore the maker workflow