Rakeway Engineering might be able to machine one for you as a solid replacement.
I bought a solid flywheel and uprated clutch from them as a replacement for the DMF on my defender 110. They're really helpful and know their stuff and the parts are excellent quality.
Beware of solid replacements, there seems to be a problem with crankshaft failures associated with replacing the DMF with solid on some Transits. Being a 6, the BMW crankshaft might be even more likely to fail through lack of torsional vibration damping.
