Difference btw surfaces and extrudation

I’m new on grasshopper and I try to make a parametric perforated volume. So I already make a parametric surface. and now I’m blocked to the next step : making the difference btw the surface and the circle to have a perforated surface and to extrude it. Does someone know how to do that, or can help me ?
I attached the file just here :point_down:
testparametric perforationgh re-2.gh (16.0 KB)
testparametric perforationgh re-2.3dm (3.1 MB)

Thanks a lot


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testparametric perforationgh re-3.gh (17.8 KB)

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Exactly thanks so much !