I've just ordered some FRs and I'm going ahead with an idea I had.
1) a CHP-90 version of this
That one's a 4 litre "cuboctahedron" made with 6mm birch ply and internal bracing.
The new one is undergoing some refinements:
More sides.
Probably dropping the internal bracing.
The vision is to hoist the boxes up on strings so that dipole vibrations and bending modes can benignly radiate like a DML. One option is to use thin hardwood slats, which cleanly transfer vibrations with minimal internal losses, but at the same time the structure is thin and light enough for the air to damp it and prevent unwanted bell modes.
