Eg: Technische Nothilfe or TeNo:

There were also some trade and shoulder strap badges, in the case of the shoulder strap it was used to denote 'technical'.
I don't think this badge:

Is
specifically RAD either(?).
Dig about and there's quite a few.
My sister bought me the rather strange 'Flags of the Third Reich' by Brian Davis a while back, I laughed at first but it's actually fascinating on the design, political control & manufacture of Nazi flags and banners. Say what you like about the Nazi's but it can't be denied that their imagery had a certain 30's stylishness.