I want this someday
My web search led me to this page, including a catalog of Tweed mixers (see the link on that page).
I particularly like the one that I've linked to (see photo to the left). Someday... [sigh...]
There was also an article on that website about the "original" 4-track cassette recorders. This one is very similar to the model that I had.
Or, rather -- I still do have it. It's in a box somewhere.