How do i make a void family from a slab that is 5 cm bigger in all directions?

I have a case where i need to create voids in a floor that fits local immersions of units placed on said floor.
I figured out how to make void a void family that consist of many voids. (I union’ed all solids into 1 solid before making the family. This way the placement of voids will match with jus alligning one void correctly.
My issue is that these immersions arent rectangular, so that scaling dont work as the proportions of the angles and lengths of sides will differ (sorry for my bad english).
Pictures are of script, result of 1 of the floors and voids, and the .dyn file
nedsenk_v5.dyn (23.1 KB) Snag_1aaf2178

Went at the problem from a diff angle and it got solved with a short and easy script…