I was watching an episode of "Yard Crasher" and the show did a backyard bar with a built in blender that appeared to be one in it. A little, OK, allot, of research and I was able to track down a website that carries them.
Kitchen Center - Food Processor
They are pricey but you can get the indoor or outdoor model plus it looks like most of the original accessories are becoming available again. These are not actually Nu-tone, but the website says that most of the accessories are compatible. The new ones are electronic now instead of mechanically controlled which might be a plus and easier to maintain.
I was pumped to see it since I had seen the Nu-tones in Airstreams from the '70's and '80's and originally wanted one for our Airstream until I found a mid 1930 Waring Blendor that works perfectly.
Good luck if you are looking for accessories for existing Nu-tones or if you want a built in blender for your Airstream.