How to make a thin sphere with a hole?

Question

I've spent last three days trying to create a model of a planet for 3D printing with a displacement applied to its external surface and one of the polar caps removed so to create a something like a bowl.

It's essentially a thin (but not zero thickness) sphere with rough surface on the outside and smooth on the inside. Here is what I did:

1. Create large sphere, unwarp it, apply planet texture a a displacement.
2. Create smaller sphere inside the large one, invert the normals.
3. Join the two.
4. Create a plane and subtract it from the 3.

The problem here is that subtraction of a plane does not create bowl "opening". It remains closed, albeit the boolean subtraction works. But it looks like a solid sphere with one of the caps cut and not like a bowl.

What am I missing here? Thanks!

Answer 1

If you use booleans, use solid meshes as cookie cutters, not planes. A cylinder maybe.

Inverted normals and an inner surface are indeed a good idea.

Also kill any selection and hit my favorite shortcut: CTRLALTSHIFTM to check for any problems with the mesh. Ideally no verts or edges should get selected. Booleans like perfect watertight topology. Just like 3D printers.

Then you can subtract the cylinder and have holes in your egg shell.

Or you simply delete a few edgerings, select the rim and connect them with the bridge tool.