Here is a link to a recent news item from William & Mary College in Williamsburg Virginia. A student took on the challenge of building a contrabass recorder.
a family of recorders – the contrabass is to the right
On the right, Evan Callaway and his Contrabass Recorder
my bass recorder – seems rather large but nothing compared with the contrabass
the alto (treble) recorder is smaller again
Janet's thread 
I had a bass but it got burgeled. Can you believe it? It made me essential sometimes. Now I haven’t played the recorder for years. I don’t even remember the fingering. I need to get it out. Alto is my favorite. I have a tenor as well, but always had trouble with the bottom notes
I think the contrabass is only useable for tall people:))