The maker of the very small F-Tuba, Bernd Jestädt, now offers a small Bb-"Tuebchen" ("Little Tuba").
On the Website of B.Jestädt (http://www.jestaedt-instrumente.de) some details are given: Height 80cm, Weight: 5.2 kg, goldbrass and silver, 19,5 mm (0,77!) bore-size, minibal.
I found a news article about that via google. It says, the Bb-Tuebchen costs 3900 Euro in the 4-valve-variant. And it says they were on the Musikmesse in Frankfurt.
Has someone here been in Frankfurt and tried these?