No info about availability.
Synthacon VCF
Resynthesis CGS-35 Synthacon VCF Panel only (for DIY) the filter is from the Steiner-Parker Synth using a diode string in a Moog filter configuration.
http://www.bigbluewave.co.uk/resynthesis/resynthesis_front_panels.htm
These merchants probably sell this module. Huh?