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ShapeMason

Mesh to solid

Triangle meshes become solids that CAD can edit, instead of reference-only meshes. How it works: Mesh to a STEP solid.

Modify a downloaded printable part in CAD

Section titled “Modify a downloaded printable part in CAD”

“I downloaded a holder for my shelf, but the slot’s a bit too narrow. My design app opens it but won’t let me change anything.”

You downloaded a bracket STL and want to widen a slot and change the screw holes, but your CAD tool treats STL as reference only.
Input bracket.stl
Output bracket.step
Works with Shapr3D, Onshape, Fusion, FreeCAD; Printables, MakerWorld, Thingiverse
Available in Web app · App · Shortcuts · CLI
Open the STL, keep Mesh to Solid (STEP), turn on Prismatic conversion. The 3D preview shows the merged faces.

What it does. Merges coplanar triangles into flat faces (a cube becomes 6 faces, not 12 triangles) and, with Prismatic conversion, turns faceted holes and bosses into true cylindrical faces bounded by real circles.

Why. Flat faces and real cylinders can be pushed, pulled, resized and filleted in CAD. A triangle soup can’t.

Tips

  • Only cylinders with square-cut ends are recognized. Countersinks, spheres and fillets stay as flat facets, which still work with booleans.
  • Origin › Bottom center (--origin bottom-center) sits the part on z = 0, centered.
  • If the part comes out 25.4 times too small, see fix a model made in the wrong units.

Repair a broken mesh

Section titled “Repair a broken mesh”

“This file I downloaded keeps giving me an error that it’s broken or not closed, but it looks fine when I look at it.”

A model fails to convert because it has holes and flipped faces.
Input broken.stl
Output broken.step
Works with Any CAD tool; often older Thingiverse models and quick exports from sculpting tools
Available in Web app · App · Shortcuts · CLI
When the report says the mesh isn’t watertight, click Repair Mesh and Retry.

What it does. Drops duplicate faces, welds cracks, makes the triangle winding consistent and fills small holes, then converts. The report says what it fixed (repair: removed 1 duplicate face(s), flipped 1 inconsistently wound face(s), filled 1 hole(s)).

Why. CAD needs a closed, consistent shell to make a solid, and most real-world meshes have small defects.

Tips

  • Badly broken meshes may still fail. Analyze shows the open and non-manifold edge counts.
  • If cracks remain, raise Merge distance (--merge-distance) a little.
  • If the mesh is open on purpose, see keep an open scan as a surface.

Bring a game asset or Blender model into CAD

Section titled “Bring a game asset or Blender model into CAD”

“I’ve got a helmet from a game that I want to build for cosplay. When I open it in my design app, it’s tiny and lying on its back.”

A prop maker has a helmet as a GLB and wants to add mounting tabs in CAD.
Input helmet.glb (or glTF, OBJ, PLY)
Output helmet.step
Works with Blender, game asset stores, Shapr3D, Fusion
Available in Web app · App · Shortcuts · CLI
Mesh to Solid (STEP); set Units to Meters and Origin to Bottom center. glTF is turned Z-up automatically; for OBJ and PLY from Blender, set Up axis to Y.

What it does. Reads node transforms and base colors, turns Y-up content to CAD’s Z-up, scales from meters and sits the model on z = 0.

Why. Game and Blender assets are Y-up and in meters; CAD expects Z-up millimeters. Without this, the model arrives on its back and 1000 times too small.

Tips

  • Organic meshes stay faceted. Expect many faces and a big STEP; it still works with booleans.
  • Analyze warns when the largest dimension is under 3 mm or over 3000 mm, which usually means a unit mistake.

Keep an open scan as a surface

Section titled “Keep an open scan as a surface”

“I took loads of photos of a car panel and an app turned them into 3D. It’s just the outside skin, but I want to use it as a guide in my design app.”

A photogrammetry scan is one open surface, not a closed solid, and you want it in CAD to model against.
Input panel-scan.obj
Output panel-scan.step, a surface body
Works with Scanning apps, reverse-engineering in CAD
Available in Web app · App · Shortcuts · CLI
When the report says the mesh isn’t watertight, click Import as Surface Body.

What it does. Converts the open mesh anyway, with a warning; CAD imports it as a surface body.

Why. Scans are open by nature, and a surface is still useful for measuring, projecting and modelling against.

Tips

  • A surface body has no volume and only limited booleans.
  • Large scans make large STEP files. Decimate the mesh in another tool first if CAD struggles.

Convert one object from a multi-object file

Section titled “Convert one object from a multi-object file”

“The file has the whole box, the lid and the little door all in one. I only want the lid.”

A 3MF holds an enclosure base, a lid and a battery door, and you need only the lid.
Input enclosure.3mf (or a multi-object OBJ or glTF)
Output lid.step, only the lid
Works with Bambu Studio and PrusaSlicer projects, multi-part downloads
Available in Web app · App · Shortcuts · CLI
Mesh to Solid (STEP); type the object’s name or id under Selection › Object. The report’s Analysis lists them.

What it does. Converts only that object, keeping its units and transforms.

Why. Faster and smaller than converting everything when you need one part.

Tips

Tune face merging on a noisy mesh

Section titled “Tune face merging on a noisy mesh”

“The flat sides of this model come out as loads of tiny slanted pieces instead of one smooth side, which makes it really hard to work with.”

An export has tiny rounding errors, so faces that should be flat come out as many slightly angled facets.
Input housing.stl
Output housing.step, cleaner flat faces
Works with Exports from sculpting tools, scanners and older CAD
Available in Web app · App · Shortcuts · CLI
Mesh to Solid (STEP); raise Coplanar angle and Coplanar distance (Advanced) while you watch the 3D preview.

What it does. Loosens how close triangles must be to count as one flat face (defaults 0.5° and 0.005 mm).

Why. Fewer, cleaner faces make the body easier to edit and the file smaller.

Tips

  • Too loose, and faces that really differ merge, subtly changing the shape. Raise in small steps and compare in the preview.
  • Turning off Merge coplanar faces (--no-merge-coplanar) keeps one face per triangle, which helps when debugging an import.

Fix a model made in the wrong units

Section titled “Fix a model made in the wrong units”

“The part I downloaded came out the size of a grain of rice. I think whoever made it measured in inches.”

A part designed in inches arrives as an STL with no units, so it comes in 25.4 times too small.
Input adapter.stl
Output adapter.step at the right size
Works with Files from US designers, older CAD exports
Available in Web app · App · Shortcuts · CLI
The report warns about the size; set Units to Inches.

What it does. Reads the coordinates as inches and writes a correctly sized STEP.

Why. STL has no units, so a wrong guess silently makes a wrong-sized part.

Tips

  • 3MF records its unit, which From file (the default) uses.
  • Scale (--scale) covers odd cases, such as a model exported at half size.