How to perform a preview when creating a block?

Hi, there.

I wonder how can I create a temporary body/feature for preview purpose just like NX did in the 'Create Box' command.

I've noticed that there's a sample 'ExtrudeWithPreview' project, but all it does is creating a extrude feature which shows up in Part Navigator.

The solution is not a must for me, but it just keeps tugging at my heartstrings.

Thanks.