Forma3D · STL mesh editor

Edit STL files on iPhone and iPad

Forma3D is a touch-first 3D mesh editor for makers and 3D-printing enthusiasts who need to inspect, modify, repair, and prepare STL or 3MF models without opening a desktop editor.

Guide updated October 24, 2026 · Published by Forma3D · iOS 17 or later · Check the App Store for the latest release

View Forma3D on the App Store

What you can do with an STL mesh

Edit vertices, edges, and faces

Switch between Object Mode and Edit Mode. Select components with single-tap, rectangle, oval, brush, multi-select, loop, and ring tools. Move, rotate, or scale using the gizmo or numeric controls.

Modify mesh geometry

Use extrude, inset, bevel, bridge, mirror, revolve, remesh, simplify, and subdivide tools. Flat, smooth, wireframe, matte, and X-Ray viewport modes help inspect the result.

Boolean and cut models

Manifold CSG supports Union, Subtract, and Intersect. Manifold cut tools include line, ellipse, circle, rectangle, polygon, curve, path, and freehand shapes, with split and array workflows.

Prepare parts for printing

Separate a mesh by sharp edges or face-paint regions. Add print-fit joints and tolerance with the Constructor workflow, then export a selected, visible, or complete scene.

Supported model workflow

Import STL, 3MF, OBJ, PLY, DAE, ABC, USD, FBX, GLB, USDZ, and native .blend scenes from Files or another app.
Inspect measurements with the ruler, millimeter or inch units, world grid, and snap-to-grid.
Paint individual faces or regions and export per-face color data in 3MF.
Export STL, 3MF, OBJ, FBX, GLB, or USDZ for the next step in a slicer or 3D workflow.
Save a native `.forma3d` project with the scene state; ZIP archives containing STL or 3MF files can also be inspected.

On-device processing: core mesh editing and rendering run locally. Forma3D does not send a model to a cloud service for mesh processing. Any upload to a slicer or cloud platform is a separate action chosen by the user.

Who is this useful for?

Use Forma3D to fix a downloaded STL, change a model before printing, split a large part, add a cut or Boolean feature, inspect non-manifold geometry, or make a quick edit on an iPhone or iPad.

For common follow-ups, see the split STL tutorial for dividing an oversized model into printable parts with alignment joints, and the painting guide for coloring faces before a multi-filament 3MF export.

Looking ahead to Apple's foldable? See our iPhone Duo, Apple Pencil & STL editing guide — what's confirmed and what to test on day one.

Frequently asked questions

Can I edit STL files on iPad or iPhone?

Yes. Forma3D imports STL, 3MF, OBJ, PLY, DAE, ABC, USD, FBX, GLB, USDZ, and .blend files and lets you edit vertices, edges, and faces, apply extrude, inset, bevel, and Boolean operations, then export the result — entirely on the device.

How do I fix a broken or non-manifold STL?

Import the file, inspect it in wireframe or X-Ray mode, then repair holes, flipped normals, and non-manifold edges with the mesh tools before sending it to a slicer.

Does mesh editing run on-device or in the cloud?

On-device. Forma3D does not upload your model to a cloud service for mesh processing; uploads to slicers or platforms are separate actions you choose.

Is Forma3D free?

Forma3D is a free download. Full-access features require an in-app purchase with monthly, annual, and lifetime options — check the App Store for current pricing.