I don't own one but I have lusted after one for a while. I think they are quite rare. A few years ago a company remade them or had plans to remake them but I never saw them in stock at any Amiga online shops.
If you check Alfred Faust's site (Bars and Pipes) he knows a lot about them too.
If you have the skills to make one yourself good luck. More than 16 channels of MIDI on an Amiga is a bit like the holy grail to me )
