Module is available as a DIY project only.
No info about availability.
Sound Effects Synthesizer
From the MFOS website (Ray Wilson): The WP-20 Sound Effects Synthesizer does just what it's name implies. It creates sounds synthetically by means of electronics. It comes very close to imitating many real sounds and can also create sounds that do not occur in real life. It performs this magic through the use of an oscillator, bandpass filter, envelope generator, low frequency oscillator, amplifier and a white noise source.
http://www.musicfromouterspace.com/analogsynth_new/THE_CAVE/WP20/WP20_PG1.html