Three operators do all the heavy lifting in OpenSCAD modeling: union , difference , and intersection . Master the order rules, learn the printability gotchas, and you'll understand the bones of every parametric part you'll ever write.
Merges all children into one solid. This is the default — if you list shapes side-by-side without wrapping them in another operator, they are implicitly union'd. You almost never need to type union() explicitly.
Computes A − B − C − ... — the first child is the base, every subsequent child is subtracted. Order matters. If you swap the cylinder above the plate, the plate gets carved out of nothing and you get an empty or inverted result.
If a subtracted cylinder ends exactly at the plate surface, OpenSCAD can produce a zero-area coplanar face that fails the manifold check. The fix is trivial: start the cylinder 1 mm below the plate and make it 2 mm taller. The AI CAD agent does this automatically for every hole it generates.
Keeps only the volume shared by all children. Use it to mask one shape with another — get only the part that lies inside both.
Hollow out any solid by subtracting an offset version of itself:
Add solid bosses, then subtract clearance holes — order matters but the pattern is rote:
Subtract both a through-hole cylinder and a tapered cone from the top face:
Force OpenSCAD to perform the full CGAL render on a subtree (even in F5 preview). Use when a large boolean is too slow to interact with — render it once, work around the cached mesh.
The AI CAD agent generates booleans with the right overlaps and runs manifold + printability checks after every render. You just describe the part.