Lungo3D

Lungo3D opens the CAD file someone just emailed you - STEP, IGES, BREP - and lets you actually work with it. Not a preview. Not a screenshot. The real solid model, on a real geometry kernel, ready to measure, cut, fillet and export.

It runs entirely on your Mac or PC. No account, no upload, no browser tab. The file never leaves your machine, which matters when the drawing belongs to a client.

Highlights

1. Opens the formats engineers actually send - STEP, IGES, BREP and STL. Double-click a file in Finder and it opens in Lungo3D, the way a desktop app should.
2. A real solid modelling kernel, not a mesh trick - built on Open CASCADE, so a curve stays a curve. Fillets, chamfers and booleans behave the way they do in the CAD package the file came from.
3. Edit, do not just look - sketch, extrude, revolve, loft, sweep, move, rotate, scale, mirror and array. Around sixty modelling commands, on the model you opened.
4. Measure with confidence - length, angle, area and volume, shown in the unit you choose. Millimetres, centimetres, metres or inches, switched at any time without touching the model.
5. Snapping that finds the point you meant - endpoints, midpoints, centres, intersections, tangents and points on a surface, with axis and object tracking.
6. See how the model is built - a document tree for walking the structure and a property inspector for reading and changing exact dimensions.
7. Export to what the next person needs - back out to STEP, IGES or BREP, or to STL, OBJ and PLY for 3D printing and rendering.
8. Automate the repetitive part - a macro editor and a visual, node-based programming plugin ship in the app for the jobs you do more than once.
9. Yours, offline - no cloud round trip, no telemetry. It opens as fast without a network as with one.

How it works

Open the app and drop a file on it, or double-click any STEP or IGES file in Finder. The model appears in the viewport with its structure listed beside it. Shift and drag to orbit, the middle button to pan, the wheel to zoom - and the status bar tells you which is which, so there is nothing to memorise.

From there it is an editor. Pick a face and fillet it, cut one solid out of another, measure the wall thickness a supplier is asking about. Save as a Lungo3D document to keep the full model tree, or export to STEP when it is time to send it on.

Lungo3D is built on Chili3D and is therefore released under the AGPL-3.0. You can download the source code here .

Perfect for

1. Engineers and designers who receive CAD files and need to check, adjust or measure them without opening a seat of the full package.
2. Makers and 3D printing - open a STEP model, repair or adapt it, export clean STL.
3. Machinists and fabricators checking dimensions and clearances straight off the customer's file.
4. Students and teachers learning solid modelling on a real kernel, without a licence server.
5. Anyone handling confidential drawings that must not be uploaded to a web service.