Union/Subtract shell shapes


I’ve made two offset ‘shell’ shapes, one is a one side open beam and the other a mountain like shell shape.

I want to join these two shape so the side where the beam and the bottom of the mountain, creates a the whole for the shape.

To make it more clear what my endgoal is, I want to make chocolate shapes like the picture added.

Mesh > union doesn’t work.

Goal of my project


Hello - it’s hard to say without a file to look at but if you are usnng meshes, MeshBooleanUinion/Difference/Intersection is probably what to use, probably, but I would not use meshes in Rhino as a rule - there are not a lot of tools for mesh modeling and the mesh intersection ‘guts’ needed for trimming and Booleans is, well, weak in Rhino.