Easy way to cut bodies with drawing lines after Shell function?

Hi Guys, Im just learning and find it very hard to create simple woodworking drawings fast since some tools speed up the process and some slow it down a lot. When creating something out of wood its all separate pieces so when i sketch and then create the body to use the shell tool I easily get the basic shape of what i need. But then I would like to separate the top and bottom since both pieces are separate pieces of wood and i need the exact dimensions in de drawing. Is there any way to do this fast? The other solution is to create two squares, connect the lines and pull the separate bodies out.

This is the difference between both methods: Dropbox - Screenshot 2022-11-04 at 20.41.22.png - Simplify your life