Sweden

BA Hobby Construction

The BA stood for Bengt Andersson who in the mid 1980's decided to manufacture a 'home' build helicopter called "Stinger".  Although reasonably successful the end product turned out to be rather heavy and thus not suitable for aerobatics.

http://www.busybee.balsta.tv/  -  Link to Dan Johansson page covering the Stinger and his restoration of one.