3D WORKBENCH / INSPECT BEFORE YOU PRINT
Check what an STL actually contains. Measure it, find open edges, choose its orientation and resize it to a real dimension — without uploading your design.
DRAG TO ORBIT · FOCUS + SCROLL TO ZOOM · ARROW KEYS ROTATE · VERTICAL = STL Z
Preview only. No cut cap is added; the complete model is exported.
Apply a model to compare it with your chosen build volume.
The measured output and diagnostics will appear here.
No general self-intersection or wall-thickness test. A clean edge report is not proof of a valid solid or a printable part.
LOOK PAST THE RENDER
Waiting for an inspection.
Diagnostics match the float32 millimeter STL offered for download. Exact-coordinate matching: nearby vertices are not welded. Up to 2,500 problem edges are highlighted.
| Check | Count | Meaning |
|---|---|---|
| Waiting for a model. | ||
A PRACTICAL SECOND OPINION
A 40-unit edge can mean 40 mm, 400 mm or 1,016 mm. STL stores triangle coordinates, not a standard unit declaration. Choose the original design unit before you resize.
Output is translated so minimum X, Y and Z are zero. Import the downloaded file as millimeters. Orientation changes are fixed 90° axis rotations; they do not mirror your part.
We compare the oriented bounding box with a rectangular X × Y × Z build volume, subtracting your margin from both sides of X and Y. The model is centered in the preview; exports start at zero.
Supports, brims, toolhead clearance, circular beds, machine keep-out zones and optimal rotation are not modeled. Maximum scale is a bounding-box limit, not a recommended manufacturing setting.
Volume is withheld for detected open or non-manifold geometry, duplicate or degenerate facets, winding conflicts, inward winding and multiple edge-connected components.
For one qualifying component, we sum signed tetrahedra about the bounding-box center. The estimate assumes a non-self-intersecting solid; self-intersections are not tested. It is not mass, infill, cavity capacity or material consumption.
Area = ½ Σ |(b − a) × (c − a)|
Signed volume = ⅙ Σ (a − o) · [(b − o) × (c − o)]
The block example measures 40 × 30 × 20 mm. Its surface area is 52 cm²; its volume is 24 cm³. Scale it to 50% and the length halves, area quarters and volume becomes one eighth: 3 cm³.
The L-bracket has a 325 mm² profile extruded by 30 mm: 9.75 cm³. The washer uses 64 straight-sided segments; its mesh volume differs slightly from an ideal circular washer.
A boundary edge belongs to one triangle; a non-manifold edge to more than two. A winding conflict means adjacent faces traverse the shared edge in the same direction. A non-manifold vertex includes disconnected face fans.
We preserve facets and vertex order. Recomputed normals do not repair winding. Binary output uses float32 coordinates, discards color/attribute bytes and may round coordinates; the preview and report inspect those actual output coordinates.
Files are read in your browser, not uploaded. No file content, model name or coordinates are sent by this tool, and nothing is saved between visits. Site-level consent and privacy information are in our privacy policy.
Up to 10 MiB and 100,000 triangles. One complete line-oriented ASCII solid or a binary STL with exact count/length matching. Non-finite values and coordinates outside ±1 billion source units are rejected.
Format reference: Library of Congress: STL. Practical context: Prusa: corrupted 3D models.
Designed and maintained by FastTool · Method documented October 14, 2026 · Not engineering certification · Report a reproducible issue