What's the equivalent of Rhino's "create solid" from bouding surfaces in Grasshoipper?

[Grasshope (Ji)]

As shown below :

[HS_Kim]

Check Boundary Volume(Intersect–>Shape–>Boundary Volume)

[PeterFotiadis (Pfotiad0)]

I don’t know if there’s a native component for doing this (because I don’t work with components - at all) … but the Method is exposed in the R SDK:

If you want an entry level C# that does that (result(s) are very slow mind) notify.