From the end of the day yesterday:

This is still not manufacturable, and is still missing all the mechanical features too. But it's getting there! By combining a skin lattice (which my part definitely needs in at least some regions, for instance the clamp faces) and a minimal, bonelike volume lattice, I hope to be able to create something that's significantly lighter than a comparable tube-to-tube (e.g. welded) structure.

The next step, I think, is to reintroduce the mechanical features (at least some of them) into the model *before* I remesh the surfaces. I would really want the mesh density to be created relative to the kinds and intensities of the forces that the part is going to be under: for instance, all of the bolts and clamp faces will want higher density meshes around them, etc. At the moment my best bet is to do that manually, by selecting areas I want to be at higher densities and just remeshing them to suit my intuition.

More soon :)