Micro Module
This Module is currently available.
Suboscillator
This 1/3 height micro module creates 2 outputs of square waves, one and two octaves below the incoming signal. It also produces another output 2 octaves below the incoming signal with a Pulse wave. There is also a mix output where the levels of the additional sounds can be controlled and combined with the original signal.
These merchants probably sell this module. Huh?
Tangible Waves uSUBOCTAVE