Plywood thickness

What thickness of plywood have you used for the interior as well as exterior walls of your build? If you have insulated - what thickness insulation foam board have you used?
After exploring the idea of a "foamie" build I am blown away that you can build almost the whole thing out of foam board and have it be structurally sound.
I am considering the idea of using just 7/32" plywood for both the interior and exterior walls and putting 1.5" foam insulation in the middle. This is a huge departure from my original plan of using 1/2" plywood on the interior and exterior.
After exploring the idea of a "foamie" build I am blown away that you can build almost the whole thing out of foam board and have it be structurally sound.
I am considering the idea of using just 7/32" plywood for both the interior and exterior walls and putting 1.5" foam insulation in the middle. This is a huge departure from my original plan of using 1/2" plywood on the interior and exterior.