Hi everybody,
I always wanted to add a tumbler reverse to my ML10, buying or making one.
Didn't know about the Dave Goodwin one, but another was sold by mr. Dave Noble:

when I contacted him (2010), he hadn't any of them anymore and subsequent requests to buy some form of drawing got no replies.
Another model of tumbler was described by mr R.G.Seiman on Model Engineer (19 october 1979) in the following interesting article::

I found these pics on the web some time ago, so I can't give credits to the people who uploaded them..
After seeing the model shown in Robbo's post, I think I have no more excuses and I have to decide which one I'll make.
Cheers,
Massimo