Which command to create internal void?

attached a simple solid created from extrusion of a rectangle, within which is a simple cylinder using cylinder tool.
I need to knockout the cylinder shape (on layer tick holder) within so as to calculate amount of solid remaining as cubic mm.

Boolean difference was my weapon but it failed to shoot !

create void with solid how.3dm (45.1 KB)

As far as I knnow Rhino isnt able to do that, you would need to connect the cylinder to the box.
But if you just want to calculate, why not substract the cylinder from the box?
Box 72019.2977 - Cylinder 3268.513 = 68750.7847

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oh, never thought that.
I am representing a silicone mould and calculating volumes as well as displaying the steps in the process, this cylinder was in fact just part of a larger object.

I then split the silicone and pull apart to show the item inside etc.

would I have to run a minute diameter ‘rod’ to the outside of the blue solid from the object inside ?



I have to run a minute diameter ‘rod’ to the outside of the blue solid from the object inside ?

Thats what I normally do, probably there is another workaround.

Dont you need a hole to let the material in/air out anyway?

Also if you split it to show the inside, you could use this parts and and add them together(the calc).

Moulds always have either to be split or to include a filling hole (often supplemented by venting holes) so Rhino copes with them. However with the advent of 3D printing it has become possible to create a physical solid with a fully enclosed void - rhino will need an enhancement to handle this…

Just tested with a cube enclosing a sphere and it works fine with Simplify3d. Just exported as an stl.
Model in Rhino

Then in Simplify.