Mesh sections and silhouettes as DXF

Rebuild a mesh as a parametric part

When you'd rather rebuild a mesh properly than convert it, start from sketches of it. Cross Section cuts an STL, 3MF, OBJ, PLY or glTF mesh with planes at the positions you choose; Project Silhouette looks along an axis and draws its outline. Both write a DXF sketch you can trace, measure or extrude.

Before and after

Before: bracket.stl	After: sections and silhouette

The sample bracket.stl cut at Z = 2 and Z = 5 mm (one DXF layer per cut, Z_2 and Z_5), and projected along Z (layer OUTLINE_Z).

Steps

In the web app

1. Open shapemason.com and drop the mesh on the page, or use Open Files.
2. Choose Cross Section (DXF) and set Section › Axis and Positions in mm, or choose Project Silhouette (DXF) and set Axis.
3. Choose Convert. The preview shows the section as you change the positions.

In the app for Mac, iPad and iPhone

1. Drop the mesh on the window, or open it with + on iPad and iPhone.
2. Choose Cross Section (DXF) or Project Silhouette (DXF) and set the axis and positions.
3. Choose Convert (⌘R on a Mac).

On the command line

shapemason section bracket.stl --at 2,5       # two sections in one DXF
shapemason section bracket.stl --axis x --at 10
shapemason project bracket.stl                # the outline seen along Z

What people use it for

• Fit checks. Overlay a section on a circuit board's outline to check clearances inside a printed case.
• Stacked laser-cut models. One section per sheet thickness.
• Foam inserts and shadow boards. The silhouette of a tool, offset for clearance.
• Drilling and mounting templates. The footprint of a part, at full size.

A position outside the mesh is a warning and gives nothing for that cut; Analyze shows the mesh's size. The mesh options (units, up axis, origin, object, repair) apply, so sections line up with a solid converted from the same file.