I know very little about Roto but an Italian correspondent has told me:

• The company Roto srl was founded in 1972 by Eugenio Rampinelli and Giorgio Antonelli in Monterenzio, about 30 km south of Bologna, Italy.
• In the mid 1970s Roto acquired a brand called REG, which sold literally tons of cheap, relatively nasty, bicycle accessories. I remember tacky chromed steel bottle cages, terrifyingly thin, squashy, plastic bottles, spot-welded steel rear carriers etc. etc..

From a British perspective Roto and REG were both imported to the UK by Ron Kitching.

The most famous (infamous?) Roto derailleurs were the jazzed up copies of the Huret Svelto. The combination of these slightly ludicrous Roto derailleurs and the surreal tackiness of the REG products always made me think that the people at Roto must have had a wicked sense of humour.

By 1982 Roto had two new derailleur models, the Roto Competition and the Roto Scorpion that was a madly cubist derivative of the Huret Eco.

A final derailleur-related point is that Eugenio Rampinelli also appears to have been the Italian importer of Zeus components.

Roto still exists, is still based in Monterenzio, and eerily, it sells bottles, bottle cages and all manner of relatively inexpensive bicycle accessories. It is a modern equivalent of REG. Unfortunately the quality looks much better - so I fear that the ironic sense of humour may have passed into history.