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Changelog

What's new in Preview3D, release by release.

v1.4.2 · Mac, iPhone & iPad

LatestOctober 2026

Fixes

  • An STL opened straight into Wireframe drew every one of its triangles — a solid smear on a detailed model — and only switching to “Shaded with edges” and back gave the clean view. Wireframe now always shows the model's edges and outline, whichever window it is in and whatever came before.

v1.4.1 · Vision Pro

October 2026

STEP

  • A small part in a large file came out coarse — a 6 mm gear had a sixteen-sided bore and a faceted hub. How finely a curve is divided now follows the part's own size rather than the file's units; small parts come out smooth, large ones are unchanged.
  • More shapes are tessellated correctly: very large curved faces, cones, tubes, bands on tori, swept and revolved faces, and holes in round faces. More models come out watertight, and volumes are much closer to the real ones.
  • A narrow strip on a large curved face used to be triangulated across the curve instead of along it — two straight chords where a rail should bend. Fixed.
  • A closed spline edge could be read the wrong way round, leaving a seam where a surface should have closed. Models that reported as not watertight may now report as watertight.
  • Assemblies open faster: their parts are now cut from the mesh already computed instead of being tessellated a second time.
  • Opening another file while a large STEP is still loading stops that load inside the kernel, rather than waiting for it to finish.

Fixes

  • “Watertight: Yes” in Model info was shown in English whatever the app's language. It is translated now.

v1.4.1 · Mac

September 2026

Fixes

  • Dragging the layer slider in a G-code window moved the print only when the mouse went left and right — across the slider instead of along it. It follows the mouse up and down now, the way it looks like it should.

v1.4.0 · Mac, iPhone & iPad

September 2026

Viewing

  • The window's bar now switches how a model is drawn: shaded, shaded with its edges, or as a wireframe.
  • The edges of a STEP file are the real ones its CAD system drew, not the boundaries of triangles. A mesh gets its crease lines instead, so an STL still reads as the shape it is.
  • Wireframe keeps the faces present but unpainted, so the far side of a part does not show through the near one, and an outline traces the silhouette.

Mac

  • A new window bar, the one the other Preview apps use: the app's name at the left, the open file centred with its menu, and how it is drawn at the right.

iPhone & iPad

  • Shaded, shaded with its edges, or a wireframe — from the toolbar on iPad, or the view menu on iPhone.
  • On an iPhone held upright, a wide model used to run off both edges. It fits again.

STEP

  • A small part in a large file came out coarse — a 6 mm gear had a sixteen-sided bore and a faceted hub. How finely a curve is divided now follows the part's own size rather than the file's units; small parts come out smooth, large ones are unchanged.
  • A narrow strip on a large curved face used to be triangulated across the curve instead of along it — two straight chords where a rail should bend. Fixed.
  • A closed spline edge could be read the wrong way round, leaving a seam where a surface should have closed. Models that reported as not watertight may now report as watertight.
  • Assemblies open faster: their parts are now cut from the mesh already computed instead of being tessellated a second time.
  • Opening another file while a large STEP is still loading stops that load inside the kernel, rather than waiting for it to finish.

Accessibility

  • Panel text, legends and the file-type list are legible in both appearances — measured on screen rather than guessed — and a model stops turning by itself when Reduce Motion is on.

v1.3.3 · Mac

September 2026

3MF

  • A 3MF exported by Bambu Studio opened as an empty model. It keeps its geometry in a separate part of the file, which Preview3D did not follow. Every Bambu 3MF now opens.
  • Coloured 3MF files show their colours: Bambu Studio's filament palette and painting, and the colours a CAD exporter or converter writes into the file itself.

Inspect & measure

  • Mesh check: Model info now tells you whether a mesh is fit to print — holes, non-manifold edges, flipped or zero-area triangles, separate parts — for every format, not only STEP.

Mac

  • The welcome window, file-type settings and mesh check now appear in all nine of the app's languages; they showed in English before.
  • The File menu no longer offers Save, Duplicate, Rename or Revert. Preview3D never changes the file you open, so they had nothing to do.
  • Step through G-code layers with the arrow keys.
  • On macOS 27, a model exported to USDZ kept only one of its colours. All of them are back.

v1.3.3 · Vision Pro

September 2026

Vision Pro

  • On visionOS 27, painted and coloured models appeared in a single colour. Their colours are back.
  • The app now appears in all nine of its languages; it showed in English before.

3MF

  • A 3MF exported by Bambu Studio opened as an empty model. It keeps its geometry in a separate part of the file, which Preview3D did not follow. Every Bambu 3MF now opens.
  • Coloured 3MF files show their colours: Bambu Studio's filament palette and painting, and the colours a CAD exporter or converter writes into the file itself.

v1.3.1 · Vision Pro

September 2026

Vision Pro

  • Preview3D now runs natively on Apple Vision Pro. Open a model in a volume beside your windows, or stand it in the room at any size and walk around it.
  • Turn it with a drag, resize it with a two-handed pinch, and read its dimensions, volume and structure in Model info.
  • G-code opens with its layer slider, so you can peel a print open layer by layer.
  • Part of the universal purchase: if you own Preview3D, the Vision Pro app is already yours.

v1.3.2 · iPhone & iPad

September 2026

3MF

  • 3MF files exported by Bambu Studio now open. They keep their geometry in a separate part of the file, which Preview3D did not follow, so they showed as an empty model.
  • Coloured 3MF files show their colours: Bambu Studio's filament palette and painting, and the colours CAD tools and converters write into the file.

v1.3.1 · iPhone & iPad

September 2026

QR codes

  • Scanning a Preview3D QR code now opens the model in the app. Until now that only worked for people who didn't have Preview3D installed.

v1.3.0 · iPhone

September 2026

iPhone

  • Preview3D now runs on your iPhone — the full viewer with STEP, STL, OBJ, glTF, 3MF, G-code and the rest, the same touch controls, and AR.
  • A toolbar that fits a phone: background and ground-plane controls fold into a menu, everything stays one tap away.
  • G-code info and the colour legend fold away to small buttons, so the toolpath gets the whole screen. On iPhone they start folded; your choice is remembered.

App Clip

  • Scan a Preview3D QR code next to a printed model and see that model in 3D — and standing on your table in AR — before installing anything. Model authors can link a model straight from a code.

v1.2.1

August 2026

Mac

  • Launching Preview3D no longer drops you into a file-open dialog. You get a window that says what the app does, lists recent files, and takes a dragged file.
  • Choose which formats open in Preview3D on a double-click — STEP, STL, 3MF, G-code and the rest — right there, or later in Settings. Nothing is taken over unless you ask.
  • A background switch sits in the title bar, so you can go light for a screenshot and dark for a dark part without opening Settings. G-code windows follow it too, which they previously ignored.
  • An opened model turns slowly until you touch it, so you can see its shape at a glance. The info panel now starts open, and G-code panels can be hidden like a model's.
  • In a G-code toolpath, the up and down arrow keys move the layer slider one layer at a time, so you can walk into the print and stop exactly where you want.

iPad

  • An opened model turns slowly until you touch it, so you can take in its shape at a glance. The first touch stops it and hands control back to you. With a keyboard attached, the up and down arrows step a G-code toolpath one layer at a time.

v1.2.0

August 2026

G-code preview

  • The toolpath is coloured by what it's printing — perimeters, infill, bridges, supports — using your slicer's own palette, with a legend to match.
  • A layer slider peels the print open, so you can look inside at any height.
  • Extrusions are drawn at their real width, lit and rounded like laid-down plastic, instead of hairlines.
  • Feature types are read from PrusaSlicer, Slic3r, OrcaSlicer, Bambu Studio and Cura.

Fixes

  • G2/G3 arcs are now followed properly. PrusaSlicer's arc fitting emits fitted curves as single arc moves, which were being flattened to straight chords — crossing brim loops over each other and cutting corners off round parts.
  • The G-code window's title bar carries the app branding like every other window.

Both platforms

  • Same release on Mac and iPad — the G-code viewer lives in the shared kit.
  • Large prints stay interactive: past ~800k drawn segments the toolpath falls back to hairlines rather than dropping frames.

v1.1.0 · iPad

August 2026

Preview3D on iPad

  • First iPadOS release — a native viewer for the same formats, included in the universal purchase.
  • Place a model in the room with AR — sized to about 20 cm, whatever units the file uses.
  • Quick Look previews and thumbnails in the Files app, including STEP, painted 3MF, FBX and G-code.
  • Touch orbit, background picker and the model info panel.

Not on iPad

  • PMI / GD&T reading, the assembly tree and format conversion remain Mac-only; iPad hands off USDZ and PNG.

v1.1.0

July 2026

G-code & .bgcode

  • Open a slicer's G-code or PrusaSlicer .bgcode directly: orbit the print toolpath in 3D, switch to the embedded preview image, and read the print stats — time, filament, weight, layer height and material.
  • Quick Look previews and Finder thumbnails cover .gcode and .bgcode as well.

v1.0.0

July 2026

Viewing

  • Native macOS viewer (SceneKit / Metal) for STEP/STP, STL, OBJ, PLY, glTF/GLB, USDZ/USD, DAE, FBX, 3DS and 3MF.
  • STEP read via StepKit - a pure-Swift B-rep kernel with watertight tessellation and crease-aware normals.
  • STEP per-part colors (STYLED_ITEM / COLOUR_RGB) rendered - colored assemblies show in their real colors.
  • Painted multi-material 3MF (PrusaSlicer mmu_segmentation) rendered in its filament colors, including sub-facet brush detail.
  • Turntable / arcball orbit, configurable background and optional floor.

Inspect & measure

  • Info panel with volume, surface area, centre of mass, watertightness, bounding-box dimensions and source unit for STEP.
  • B-rep structure (solids / faces / edges) and triangle / vertex counts.
  • Instanced assembly tree of sub-parts - repeated parts are placed at their true positions and share geometry; click a part to highlight and isolate it.
  • Centre-of-mass marker you can toggle on in the view.

PMI & GD&T (AP242)

  • Semantic PMI in the info panel: dimensions with ± tolerance bands, geometric tolerances (flatness, position, perpendicularity, profile…) with zones and datum references, and datum features.
  • Graphical PMI overlay - dimension lines, leaders and symbols drawn over the model, toggleable.

Finder integration

  • Quick Look previews for every supported format - including STEP, painted 3MF, FBX and 3DS that macOS can't render on its own.
  • Finder thumbnails via a dedicated thumbnail extension.
  • File-type association, Quick Look and thumbnails now cover the mesh formats read via Assimp (FBX, 3DS, X3D, LWO, MS3D, AC, AMF, OFF…), not just the core formats.
  • Heavy STEP previews and thumbnails use a fast coarse/decimated load, so large CAD stays quick in Finder.

Convert & export

  • One-click convert: STEP → STL / OBJ / GLB / USDZ (StepKit), any loaded scene → STL / OBJ / PLY (Model I/O).
  • USDZ output is ready for AR Quick Look.
  • Export a single selected sub-part of an assembly on its own.
  • PNG snapshots of the current view at 1×, 2× and 4×.

App

  • Apple silicon · macOS 14 Sonoma or later.
  • Fully offline — no network, no analytics, no accounts.