My almost-complete project, Mostly Printed CNC Build, will allow frame creation from a variety of materials. The three that interest me the most however are:

Aluminum

Graphene-based 3D printing filament

Reinforced carbon fibre

Aluminum - The frame can be milled from a soft aluminum. The main shape of the frame, biomorphic or purely structural, can be cut out and then channeled out to reduce weight but maintain structural integrity. Wire routing may also be improved in this way. 

Graphene 3D filament - although lighter than other filaments will be a heavy option because it will take more material to achieve the structural integrity required. The entire frame will fit within the extents of the print bed. 

Carbon fibre - can be milled to the correct shape, but will be floppy until reinforced by either another layer of carbon fibre or carbon fibre tubing. This will also add to the weight.

I would like to try at least two of these materials for frame creation.