Updated 2020-11-03...When originally written (with SW2008) this macro saved a part file copy of your original file, using the defeature tool to strip out all internal volumes. It then got the surface area of that defeatured part, inserted the surface area into the custom properties of the original file and then deleted the defeatured copy.Unfortunately the defeature tool no longer works that way and the API's are still not accessible (at least in all versions of SW up to and including 2018; the year I'm using).In order for the macro to function correctly you need to run the defeature tool at least once and save the settings...menu -> tools -> defeature...A side bar will open for the tool and you need to uncheck everything and make all the selection boxes blank (except for the store settings option on the last page).left side bar -> next -> next -> next -> wait -> next -> Check “Just store my settings for future use” -> OK (Tick)If they ever unlock the API's then I will most likely update the macro but until then there is no point.The temp file was originally being saved to and then deleted from the desktop but this has proven to be a bit sketchy in regards to user privileges... not it will save to and delte from the location of the open file. So as long as you have automated write ability to that folder then you are good to go.This macro will not work with surface models.If you have never run the defeature tool before the macro will flatten the file and most likely spit out the entire surface area including internals.