"Extrude" a 3D object / minkowski / mould extraction

Hi!

i'm new to cadquery after some experience with openscad and solidpython.

I'm missing minkowsky addition for similar reasons as #274 (mould extraction). I read about the differences between CSG and b-Rep (and SDF) and I understand that minkowsky addition is not going to come any time soon.

For me it would be a nice workaround to "project" a 3D object onto a plane yielding a 2d shadow of it. This shape ("wire"?) that can then be extruded. Is there a way to achieve that? I found a few projectToSomething methods in the docs, but the seem to be meant for different use cases.

I'm also happy for other ideas how to achieve the goal. Is my brain so stuck in the CSG world that I can't see the obvious solution or is this idea of extruding/sweeping a 3d shape instead of a 2d shape so niche that nobody is bothered by the missing feature?

Cheers!