Measure everything

Bad measurements are the number one reason a first build fails. Capture reality before you ask a model to design anything.

A language model will happily design around a wrong number and make the result look convincing. The physical world is the only ground truth, so start there.

For small parts use digital calipers (about $20 to $40). For rooms, doors, enclosures and anything bigger, scan it with a phone LiDAR app such as Polycam and pull dimensions from the mesh. Photograph the object with a ruler in frame as a backup.

Write every dimension into a plain text spec: value, unit, tolerance, and how you measured it. Measure each critical number twice, on different days if you can. This file becomes the input for step 2.

Checklist

• Calipers for anything under 150 mm
• LiDAR scan for spaces and large objects
• Every dimension has a unit and a tolerance
• Critical numbers measured twice