Can someone help me to produce a very simple 3d object

[encephalon]

better late than never, if its not too late maybe the link below is a starting point?

Sweep Plane until Lower Section has a certain volume

For a simple geometry like this I don’t think there’s any need to use Kangaroo - it can be a simple geometric calculation. If this is an example leading to more complex geometries though, here’s an example I made a while ago for simulating floating objects using Archimedes’ principle buoyancy_archimedes.gh (60.1 KB)

btw your links contained empty 3dm files. but i also checked with an ipad not sure it worked.