Cotangent 2.0 Beta

Cotangent 1.0 was 3D Printing and Mesh Repair software that Gradientspace Corp developed from 2016 to 2018 - it’s still on the web here, for now. As of November 2025, we’re rebooting this project, starting from scratch and with a somewhat different focus. This page will serve as a home for the new version until we rebuild the main website.

What Does Cotangent 2 Do?

Our current focus is supporting users of Meshmixer who are working in the Medical CAD space. We’ve found that even though Meshmixer has been abandoned for nearly 10 years now, it is still widely used by doctors, dentists, prosthetists, and in many other medical-related domains. When we talk to these users, we find they have a lot of feature requests that will never be satisfied by the Fusion 360 Mesh Workspace (which is where Autodesk redirects Meshmixer users). In this intervening decade, no other software has provided a comparable easy-to-use mesh editing environment. And so for various reasons, we feel that now is the time to build a spiritual successor to Meshmixer!

We are starting with much-requested features complementary to Meshmixer, like better measurement and analysis tools, 3D text labelling of meshes, and better mesh auto-repair. Gradientspace has a substantial toolbox of geometry algorithms in the C# geometry3Sharp library, and we are leveraging the fantastic realtime mesh geometry kernel in Unreal Engine. There are many great open-source libraries for geometry processing that did not exist in 2012 when Meshmixer was created, and we aim to use whatever helps.

More details will come soon. For now, here is a brief summary of the current Feature Set and Tools:

Import/Export - OBJ and STL meshes
Scene Saving/Loading - Save/load to a binary Cotangent file format. Under the hood, this is a standard sqlite3 database with meshes serialized as simple binary blobs in an open format. So your data will never be trapped, like it is in the .mix format.
Mesh Selection - improved version of the brush-based triangle selection you know and love
Measure - measurement of dimensions and radius
Section - section plane analysis
Make Solid - a much-improved algorithmic approach based on the Fast Mesh Winding Number [ blog1 ] [ blog2 ]
Weld - weld mesh open boundaries, and also resolve T-junctions
Plane Cut - robust battle-tested mesh cutting with Delaunay Triangulation of holes
AutoRepair - mesh-based methods to remove holes and repair other mesh issues
Boolean - “quite-robust” precise mesh Boolean operations
Label - add 3D text to meshes

Meshmixer Sync

Cotan2 can import the current scene from an open Meshmixer instance, as well as push updates back to Meshmixer. We know that many professionals are actively using Meshmixer in their labs, clinics and practices on a daily basis, and can’t just up and switch to some other software that doesn’t have all the necessary capabilities. So we’ve made it as easy as possible to use Cotan2 as a sort of “Meshmixer Assistant”, providing missing features or more robust/capable versions of critical Tools without requiring you to fundamentally change your Meshmixer-based processes.

Download / Installation / Setup

Download the Current Version

Download the zip file of the current version here: Cotangent_Beta1.zip

The last update was on November 26, 2025.

Note that currently we only are supporting Windows 10/11. OSX and Linux support will come in time - if it’s important to you, reach out.

Install .NET 8 Runtime (only necessary once)

If you haven’t done it once already, install a version of the .NET 8.0 Runtime. Here is a direct link to the 8.0.21 installer, or you can go to Microsoft’s .Net 8 page and scroll down to the .NET Runtime section and follow the link for the current Windows x64 version. (There is a good chance your computer already has this installed, but it won’t hurt to make sure)

Unzip and Run

Unzip the .zip file you downloaded above, and double-click Cotangent.exe to start the app. Currently there is no installer - we’re working on it!

Follow Development

Our goal with Cotangent 2 is to get better workflows into the hands of users as quickly as possible. So we’ll be developing this app in the open, and you can follow along on Bluesky, YouTube, or the Gradientspace Discord.