CAD basics in 4 minutes

CAD stands for Computer-Aided Design. In plain English: software that lets you describe a physical object as a set of shapes the computer can measure, copy, and turn into a 3D model.

The 3D models you see on Thingiverse or Printables are CAD files — usually saved as STL. You don't need a degree in mechanical engineering to make one. You need three habits: build with simple shapes, position them in mm, and combine them with boolean operations.

1. Build with simple shapes. Almost every 3D-printed object starts as cubes, cylinders, and spheres. A phone stand is two boxes. A keychain is a disc with a hole. A cable clip is a block with a slot. ForgeSlicer's left panel has these primitives ready to drop in.

2. Position in millimetres. All sizes are mm. A phone is about 75 mm wide. A standard keyring is 5 mm thick. The build plate of a Bambu A1 mini is 180×180 mm. Get used to thinking in mm and your designs come out right-sized first try.

3. Combine with booleans. Union (combine two shapes into one), subtract (cut one shape out of another), and intersect (keep only the overlap). Three operations cover ≈ 90% of what you'll ever do.

Big CAD tools (Fusion 360, SolidWorks) are designed for engineers building cars. They have hundreds of features you don't need on day one. ForgeSlicer keeps the core 5% — primitives, booleans, transforms, and slicer hand-off — and lets you talk to it (voice commands work for almost every operation).