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I'm very new to Blender, so I think this should be an easy question to answer, but after a few hours of Googling and experimenting, I'm no closer to a solution.

I'm trying to model a blastula for 3D printing. You can google "blastula" if you're unfamiliar, but essentially I need to create a hollow ball of cells, or more simply, a sphere made of spheres. I've been able to approximate this using the methods described under "Creating a spherical array," but I can't figure out how to join the individual spheres and/or remove the overlapping vertices on the inside (for printing). I've had success using BoolTool to merge a few individual spheres, but I can't figure out how to create the blastula as a whole.

Alternatively, if there's a way to simply curve/extrude each face on a sphere such that it resembles a partial sphere itself, that may be easier, but I have no idea how to go about that. Sorry in advance if this is poorly phrased, like I said I'm very new to Blender and still learning the terminology. Thanks!

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  • $\begingroup$ "remove the overlapping vertices on the inside (for printing)" maybe the remesh modifier will help? $\endgroup$ – xlxs Aug 26 at 22:32
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    $\begingroup$ Generally Union operation of Boolean modifier (or operator in Edit mode) seems to be pretty much what you are looking for. Although recent improvements in Remesh modifier might do the job as well or better, you might try latest builds. How did you join with BoolTool, what mode did you use? What geometry was left as a result? $\endgroup$ – Mr Zak Aug 26 at 22:53
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Metaballs?

An Icosphere and a Metaball..

enter image description here

  • Icosphere Object Properties > 'Instancing' > set to 'Vertex'
  • Metaball parented to Icosphere

enter image description here

  • Icosphere (search) > 'Make Instances Real'

enter image description here

  • Metaball .. Object menu > 'Convert To' .. mesh
  • An outside face selected, Ctrl L all outside selected
  • Ctrl I all inside selected, and deleted

enter image description here

The result is manifold, and printable. It can be tweaked to a reasonable degree .. eg Alt S fattened.. and/or Ctrl V > Vertex Smoothed..

enter image description here

You might need to poke a hole in it somewhere, and give it a Solidify modifier to make it hollow and drainable,it depends on your printing method..

EDIT: The above example, was only adjusting the radius and stiffness of the metaball instances. Thanks to @GTD.. an improvement.

For more flexibility, after making the instances real, before conversion to a mesh, in Object Mode, you can add another metaball with a larger radius in the same family. Left to right: the original family-base metaball, 'Mball', its instances, and the new, larger metaball, 'Mball.xxx' The new metaball is not an instance of 'Mball', so can be edited independently, but is a member of the family.

enter image description here

After placing it at the same location as the instances, you can adjust it to fill any gaps between them, and after conversion to a mesh, the interior is clean.

enter image description here

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  • $\begingroup$ This seems to work, but when I do this the metaball isn't nearly as spherical, so the "cells" in the resulting shape don't look as defined as yours (which is pretty much just what I'm looking for). Any ideas? I've tried reading up on the metaball to understand how it works compared to the mesh shapes, but TBH it might be a little above my level of understanding as a Blender beginner. Thanks for your help, this is definitely the closest I've gotten! If I could just get the "cells" looking more spherical, I'd be all set. $\endgroup$ – GTD Aug 27 at 23:35
  • $\begingroup$ @GTD Thanks: you're right. See edit. The combination of 'Family' and 'Instancing' relations can make things confusing, in the viewport. For even more flexibility before conversion, on the cluster-instances, you can go into the Header menu, Object > Relations > Make Single User > Data and Object, so you can give the previously instanced metas in the cluster different shapes, etc. $\endgroup$ – Robin Betts Aug 28 at 9:28
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Here was my final result, I hope this is basically what you want.

final

Step 1: Make an icosphere

ico

I made mine with three subdivisions. The number of vertices on your icosphere will be the number of balls on your final result.

Step 2: Delete All edges and Faces:

Go into edit mode, press a to select the whole thing, and then press X, then select Only Edges and Faces. This makes it so the sphere is made up of just disconnected vertices.

verts

Now all you need is two modifiers.

Step 3: Add a Skin Modifier:

skin

This will create a cube at each of your disconnected vertices.

If your cubes are too big, go into edit mode, select everything and use Ctrl + A to scale the cubes.

Step 4: Add a Subdivision Surface Modifier:

Now, add a subsurf. This will turn all the cubes into spheres when you increase the subdivision number. You can also check Shade Smooth in the skin modifier to make them smoother.

final again

Note: The subdivision surface will make the cubes smaller, so you may need to scale them up again so they link together to make a sphere.

You can then apply the modifiers to get the actual mesh.

Good Luck, I hope this helps!

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    $\begingroup$ Once you have a single Mesh, make sure you Merge Vertices and for 3D printing prep use the Mesh->Cleanup options. $\endgroup$ – rob Aug 27 at 10:09

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