I made a kind of plug, the side of the plug should have splits, so it can be compressed. So first made the plug -OK ending in a closed brep
Then made the splits and then tried to find a way to turn them into pockets (negative extrude {I come from CAD program}). Only thing I could find is Trim Solid.
But that gives an open brep. Tried to close it with Cap Holes, Cap Holes Ex.
But no succes at all.
How could I avoid these open breps? And/or fix them
buisplug with open breps.gh (23.3 KB)
Thank you very much Joseph,
Could I have known this by reading/searching Internet? (I did search a lot 
)
Maybe there is some Wiki were this is concentrated info?
Many searches I do, end on the forum or here: Solid Difference - Grasshopper Intersect - Component for Grasshopper | Grasshopper Docs
What is the same info then the “help” on a component.
So maybe, there is some other/more starting point?