ScanRuler: Turning 3D Scans into Useful CAD

What it is

• ScanRuler is a free, open-source tool that runs locally, without installation or tracking.
• It helps users measure, analyze, edit, and reverse-engineer 3D scan meshes—tasks that often require expensive or complex software.
• An optional AI connection can operate ScanRuler’s tools to build or modify CAD models.

What you can do with it

• Measure scans: Fit features such as spheres, planes, and circles, then measure distances, angles, radii, and other dimensions. Fitted geometry can be exported as STEP.
• Compare against reference models: Align a scan with CAD geometry and view a deviation map. The presenter used this to compare ABS prints, identify cold-print warping, and improve scale compensation.
• Analyze wall thickness: Generate a thickness map to find thin or uneven areas, useful for quality control and manufacturing analysis.
• Edit meshes: Fix surface normals, close holes, smooth scans, and use fitted features for Boolean operations.
• Reverse-engineer parts: Create parametric sketches and features from a scan, including extrusions, fillets, and hollowed geometry. Models can be edited in ScanRuler or exported as STEP.
• Repair broken parts: Fit a designed feature to a scanned fracture surface with the “Trim to the Break” tool, optionally leaving clearance for glue.

AI-assisted workflow

1. Load a scan into ScanRuler and connect an AI agent through its MCP server.
2. Describe the part and the intended result; additional context and notes improve the outcome.
3. The agent can inspect and align the scan, fit features, create sections, build a parametric model, and check deviations.
4. Add notes to request changes or repairs, then export the finished model or refine it further.

AI assistance is optional. Results vary: the presenter reports the best performance with Opus 5.5, while complex freeform shapes, rough castings, and less capable or local models can be challenging.

Scanner tests and examples

• The video demonstrates the workflow with the Elegoo M1 Ultra, a scanner with three blue-laser modes, structured-light scanning, swappable batteries, and wireless operation.
• After calibration, repeated ball-bar scans measured within the scanner’s stated accuracy of 0.035 mm for the tested setup.
• Markerless laser scanning captured a car wheel hub, enabling measurements including wheel offset and bolt-circle diameter.
• Scans revealed wall-thickness variation in a vacuum-formed panel, with the thinnest areas around its lower bends.
• AI-assisted projects included rebuilding broken refrigerator components and designing a fitted TPU protective sleeve for a bike computer.

Takeaway

ScanRuler aims to make 3D scanning practical for workshops, hobbies, and small businesses by combining scan measurement, analysis, mesh editing, and parametric CAD in one free tool. The M1 Ultra is presented as a versatile but not low-cost scanner; the video mentions an early-bird price of $1,599.