Well... maybe we should decide what is the semantic of "lists". In this setting, a list contain a collection of objects sharing the same geometry AND color (my proposal). Lists are also used to define a kind of hierarchical structure (e.g. set -> {voxels}).I didn't know that there will be performance issues in GL.

Moving it to Board3DFactory will leave the semantic of lists unclear (at Display3D 3D level). 

what do you think?