Hi Powaybob,

If you question means how to set the thickness of a wall in Punch, just select the wall--> properties bar--> select the thickness--> if it is a custom thickness, just write the value--> press enter in your keyboard

If your question means how to set the thickness of a straw bale wall in real life, notice that straw bale construction has a special building code applications (Unsupported Wall Length, Allowable Loads, etc) therefore, the answer is not provided by a sw, but for a professional and is different for each project

In addition, you can read my article "Do I need an Architect?
http://www.punchhelpers.com/need_arch.html

Hope this helps

Patricia