I have a 67mm (ND) filter that i want to use on my rolleflex 6008i (BAY VI). Any DIY tips how to mount it safely ? I cannot justify (still available ?) a dedicated BAY VI filter.
I think Helioplan and B+W offer such an adapter, they also show up on *bay from time to time. Another, tough slightly more expensive, possibility is
to trade your lens for an EL lens, they come with an 67mm thread instead of Bay VI.