3D workflow guides

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Format conversion and interoperability Which 3D file format to convert to, what each conversion throws away, and why a model that opened correctly in one program arrives wrong in the next. Mesh repair and optimisation How to tell what is actually wrong with a mesh, why repair tools disagree about the same file, and which fixes cost accuracy. Getting an AI generated model to work downstream What a generated mesh arrives with, why it fails in slicers and engines, and which of those failures are fixable and which mean regenerating.

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3MF to STL: What 9 Converters Kept, Dropped and Invented 2026-10-09
We sent ten test files through nine 3MF to STL converters. Simple files mostly survive. A Bambu Studio project file did not survive any of them intact, Bambu Studio included.
What Size Is an AI-Generated 3D Model? Four Generators, Two Formats, Three Slicers 2026-09-30
Image-to-3D generators give a model no real size. We measured four: the same figurine is 2 m tall as a GLB and 2 mm as an STL, and three slicers each guess a different size.
Why the Same PLY File Opens in One Program and Not Another 2026-09-27
A PLY header is a schema, so two files with the same extension can have nothing in common. Here is how to read the header, and what each kind of PLY actually is.
Can You 3D Print a GPT-6 Astra Model? We Measured 1,304 Files 2026-09-24
The geometry GPT-6 Astra builds in Blender is closed and clean. What breaks it is the export: a 1.63 m model that lands in the slicer at 1.63 mm, and a stray cube one round trip away.
When a Broken Mesh Is Worth Repairing, and When You Are Just Making It Worse 2026-09-23
Auto repair can produce a closed, single shell mesh that is eleven times further from the correct volume. The watertight tick is not the finish line, and here is what to check instead.
What an MTL File Is, and Why Your Textures Vanished Without It 2026-09-20
A textured OBJ is three files, not one. We measured the chain: two hops, both by bare filename, and zero image bytes in the model file. Nothing warns you when it breaks.
How to Check a Model You Did Not Make, and Why the Order Matters 2026-09-17
One repair setting, one mesh, three apparent scales. It fixed the model, destroyed it, or did nothing. Checking size before topology is not a habit, it decides the outcome.
What GLB to STL Conversion Actually Throws Away, Measured Field by Field 2026-09-14
Two named parts, a texture, UVs, a PBR material and vertex colours go in. One unnamed blob of triangles comes out, in a file nearly twice the size. Measured field by field.
What "Same Vertex" Means in an STL, and Why Four Tools Answer It Differently 2026-09-11
An STL never says two triangles share a corner. Each tool works it out its own way, so one reports a watertight mesh and another reports 5,120 shells. Measured, with the documented defaults.
Why a 3D Model Imports at the Wrong Size: Only One Mesh Format Stores a Unit 2026-09-08
Measured across five formats: STL, OBJ, PLY and GLB write no unit of length into the file. Only 3MF does. That one missing field is why a model lands 1000 times too small or too big.
How to Reduce STL File Size: Measured Results for Every Method, Including the Free Ones 2026-09-01
Saving an STL as binary instead of ASCII makes it 5.8 times smaller with no geometry change. Measured results for that, decimation, zip and Draco, with what each costs in millimetres.
Retopology in 2026: When You Need It, When You Do Not, and What AI Can Actually Do 2026-08-25
Retopology is recommended far more often than it is required. What each destination actually demands, the order that keeps auto-retopology from failing, and which AI tools have shipped.
OBJ vs STL: What Each Format Stores, and Why One Direction Costs More 2026-08-23
STL does not share vertices and OBJ does, which decides file size, what survives conversion, and why an STL converted to OBJ arrives shattered. With measured figures.
Non-Manifold Edges: Why Sealing Every Hole Does Not Clear the Error 2026-08-20
Non-manifold and not watertight are different properties, so a sealed model can still throw the error. What the number counts, when you can print anyway, and the exact fix in each tool.
How to Convert STL to STEP: The Route Depends on Where the STL Came From 2026-08-17
A mesh from CAD and a mesh from a scan need opposite algorithms, and using the wrong one fails predictably. Exact menu paths for FreeCAD, Fusion 360 and SolidWorks, plus which methods are paywalled.
FBX vs OBJ: What Survives the Conversion and What Silently Does Not 2026-08-14
FBX carries rigs and animation that OBJ cannot. On PBR materials the ranking flips, and the reason is built into the FBX SDK. What each format stores, and how to convert without losing textures.
STEP vs STL: Converting Both Ways, and Why One Direction Barely Works 2026-08-11
STEP to STL is routine. STL to STEP is not a conversion at all, it is a rebuild. Here is what each format stores, what the converters actually output, and the tool limits nobody mentions.
What Is a GLB File? How to Open One, Look Inside It, and Convert It 2026-08-07
A GLB is a whole 3D scene in one binary file: geometry, materials and textures together. Here is how to open one without installing anything, what is actually inside, and when to convert it.
3MF vs STL: What Changes When You Switch, and What Nobody Warns You About 2026-08-04
3MF carries units, colour, objects and print settings that STL cannot. It also overwrites your slicer profile, breaks between vendors, and has a real security history. All four, with sources.
How to Repair a Broken STL File: Holes, Non-Manifold Edges and Flipped Normals 2026-07-16
A practical guide to fixing STL errors that break 3D prints, from one-click auto-repair to MeshLab, plus why AI generated meshes need it most.