Filling in blank space to make a container

Hi All

My first post as I need help, I have a cylindrical shape, inside that I have placed a 3D model.

I need to fill up the space between the outside walls of my model and the walls of the cylinder, then I want to remove the 3D model leaving a negative copy of my 3D model if that makes any sense!.

I just can’t find a fill option, I’m running pro 2021.

Many thanks in advance.


Sketchup is a surface modeller, everything is made of faces with fronts and backs. The white is the front and the gray is the back, so a solid cube is nothing more than 6 faces white on the outside and gray on the inside. These front and back faces are what tells the software, and 3d printers etc, what is air and what is material.
So having said that, if you reversed all the white faces of your inner model then traced an edge on the cylinder so a top face would form, you would have a solid with a void the shape of your model inside.

Hi Box

Thank you for your help, I just did a cylinder with a basic box inside and your right that will work.