Users / Combining Shapes (CSG)

Combining Shapes (CSG)

Cut, merge, and overlap shapes to build things a single primitive can't — no sculpting required.

CSG stands for Constructive Solid Geometry — a fancy name for a simple idea: combine two or more shapes using boolean logic, the same way you'd combine circles in a Venn diagram.

Three colored shapes in MeshCraft set up for CSG operations: a red rounded shape, a tan wireframe box, and a blue wireframe box.
Shapes staged for CSG — the hierarchy shows a Difference (ArchHole), a Union (Merged), and an Intersection (RoundedBlock).
➕
Union — glue shapes together
Merges every shape inside into one solid object, as if you welded them. Good for building complex objects out of overlapping primitives.
✂️
Difference — cut a hole
Subtracts one shape from another, like a cookie cutter or a drill bit. The shape doing the cutting is marked as the "cutter"; everything else is the base it's cut from.
🔗
Intersection — keep only the overlap
Keeps just the volume where all the shapes overlap, discarding the rest — handy for rounding off a box using a sphere, for example.

How to do it in the editor

  1. Create a CSG groupAdd → CSG → Union / Difference / Intersection. A new CSG node appears in the Scene hierarchy.
  2. Add shapes to itDrag existing objects onto the CSG node in the hierarchy panel, or select the CSG node and add new primitives to it directly.
  3. For a Difference, mark the cutterSelect the shape that should do the cutting and mark its role as cutter in the Properties panel — everything else in the group is treated as the base material being cut.
  4. DoneThe viewport updates immediately to show the real, solid result of the boolean operation.
⚠️
A couple of current quirks

The result of a CSG operation currently uses flat shading and takes on the material of the CSG group itself rather than each child's individual material. Not every shape type can be used inside a CSG group when exporting — MeshCraft will tell you clearly if one can't.

💡

CSG groups can be nested — put a Difference inside a Union, for example — for arbitrarily complex shapes built entirely from simple primitives.