Voronoi Stadium space frame Design

Hi!

I’m a student and for Design Studio I want to create an organic voronoi space frame around an existing stadium.
I’ve managed to use voronoi for a basic cube, but when I try it on my
desired shape around the stadium, which is a closed solid polygon, the voronoi structure isn’t created inside the absolute boundary, but more like inside an overall boundary (see pictures)
.
Any help on how to achieve this? Also, is it possible to assign inner boundaries where you DON’t want any structure?

Thanks a lot in advance!!!
Stay healthy,

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boundaryVolumeforStadiumShell.3dm (509.8 KB)
shell test.gh (5.2 KB)