How to shell a mesh file

hi group

i just downloaded rhino6 evaluation as i want to explore the possibilities in working with 3d scan data and 3d print files.

as a trial i downloaded an stl of a skull which is not great but ok to play with, i would like to shell it out so it will become a container to then 3d print, is this possible?
skull_plant.stl (94.8 KB)

i would then like to try and sculpt it a bit to make it better and fix some of the errors on it like the eyes and nose is that possible?


sculpting meshes in Rhino? have you read what’s Rhino for?.
I think you will have better results with programs like Meshmixer which is free.

ive been using and owned rhino since v1 but stopped at v4 as i moved onto to inventor and spaceclaim however i have not really worked with meshes and i just got a 3d printer and scanner so now need to look at 3d cad differently…
although mesh mixer seems interesting, i will check it out.

but can i shell the stl file in rhino?

you could delete the upper and the lower flat surface, then use OffsetMesh, the result is of course not like shell but maybe that brings you closer.

edit: i now read you want to make a container, so deleting the upper surface then offsetting with 1 inwards worked resulting in a valid closed good mesh.

Skull_plant.obj.3dm (104.7 KB)

1 Like

as @encephalon says, you can explode the mesh, delete the top flat mesh and then Use OffsetMesh with the option Solid but it will generate some intersections inside.

exploding is not necessary, just use subselect with cmd shift from an orthogonal side view, offsetting worked without intersection if you use solid to inwards and uncheck both sides, but ok yes when you make it as thick as you did probably :slight_smile: didnt check that much.

1 Like

for what it is worth, here a solution with Grasshopper and Dendro, it is surely not the best for the Skull as it is a quite simple geometry, but Dendro puts the power of OpenVDB in Rhinoceros. So it is a good alternative to very good mesh software like Blender, Houdini, Meshmixer …

I also use Clipper for offset

The script has 2 parts
One to extract the upper part and to make the tool to make the upper hole (I offset in 2D using Clipper).
The other part is boolean with mesh using Dendro.
The only trick I learned today is that you need to put bandwidth to 2 in Dendro in order to suppress some mesh problems.

If you want to play, use higher Voxel Size in Dendro, I used 0.15 here.
shell (29.3 KB)

The advantage of Dendro is that there are many other possibilities. For example if you want smoother inside. You can double the offset. So it will be more easy to clean …

shell (31.4 KB)