Blender Add-ons and tips for 3D printing

These are tools and techniques I'm trying out to help create meshes suitable for 3D printing. That is manifold and non-intersecting.

3D Print Toolbox

This is a useful set of tools for analysing a 3D model. It can identify if the mesh is non-manifold and  if it has intersecting faces.

https://extensions.blender.org/add-ons/print3d-toolbox/

Press the "Solid" or "Intersections" buttons to generate the statistics on the selected object.

I do not use the "Clean Up" tools. They are not as effective, in my opinion, as other methods.

Creating a Manifold Mesh

My preferred method is to join my meshes together into one object then use the Remesh Modifier.

Joining Meshes into One Object (simple and quick)

This is the fairly basic method of adding several meshes into one object.

In Object mode, select the first object then use [SHIFT][LMB] to select others.

When they are all selected, press [CTRL][J].

They will all merge into the first of the selected objects.

Remesh Modifier

I have found this a fairly reliable method to make a tidy manifold mesh out of a mess. The result is suitable for 3D printing, however, none of the options retained the originals quality.

Remesh Modifier - Blender 4.3 Manual

In my experience, only a Voxel remesh creates a manifold non-intersecting mesh. The other options, such as Sharp with an Octree depth of 10 or above, produced a better quality result, but did not help for 3D printing.

Sharp with Octree Depth = 10

The quality depends a lot on the original model.

My preferred solution to create a manifold and non-intersecting mesh, suitable for 3D printing is to use the Voxel setting, with a size of 0.03mm. That is the thinnest layer that my resin 3D printer will produce.

Remesh Voxel Size = 0.03mm

Original Version

However, it's important to keep the original model, should I need to make any edits. The remesh is always the last process just as a means of satisfying the slicer software.

This gave good enough results, and the time to process was acceptable.

For larger, or complex models, this produced a lot of vertices. 34 million in one case. As I only usually print at a resolution of 50µm (micrometres), 0.05mm, for those models, I remesh at 0.05mm.

I'll continue to experiment with this.

For scenery, where the detail is not so critical, a Voxel Remesh, with a size of 0.05mm or even 0.1mm was sufficient and quick.

Apply the modifier to be able to check the result.

The Voxel remesh is also useful to make models used for boolean difference cuts. I have found that large faces often do not cut or join very well with the boolean tools. Remeshing can help.

Separating Parts of a Mesh

In Edit mode, select the vertices to include in another object of their own and press [P].

If the vertices are all connected, using [L] to select all connected vertices is a quick way to remove whole areas.

An Alternative to Individual Boolean Unions

This method leaves a hollow shell using a Cube with a Boolean Intersect modifier.

The result is similar to using boolean unions on individual mesh objects. In my attempts to use boolean unions on lots of detailed meshes, I found that it was very time consuming and would often fail. By using the cube with an intersection, all of the individual parts are made one in a single boolean operation.

Using the cube method does not create a manifold mesh, which is disappointing.

The method to create a single mesh is:

Create or import a model made of intersecting parts.

Join all objects in to one object using [Ctrl][J].

Create a cube larger than the object. Make sure it encompasses the whole object.

Add a boolean modifier to the Cube.

Set to "intersect".

Add the multi-part object to it.

And wait.

When done, Apply that modifier.

And wait again.

The result should be a single mesh but, probably, with lots of self intersecting faces.

Auto-Merge Vertices

This is off by default, but when trying to create or keep a mesh manifold, my prior experience is that it is easier if this is on.

In Edit Mode, top right of the window.

It does sometimes make unwanted connections but they are less than the confusion of the mesh looking visually correct but still having a hole in it.

It does this as you go, it does not fix all existing doubled up vertices.

Merge all Duplicate Vertices in an Existing Mesh

This is useful for fixing exiting meshes.

In edit mode, select all the vertices [A].

Use the right click menu or [M] to merge vertices.

"By Distance" is probably the most appropriate to use.

I work in millimetres so the default distance of 0.0001 is probably appropriate.

It's useful to have the Scene Statistics enabled to see it do something.

Show the Vertices Count, Scene Statistics

This is useful when carrying out several remedial tasks.

Simply [RIGHT-CLICK] on the status bar at the bottom of the Blender Window.

Tick to enable "Scene Statistics"

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