Available as an assembled Module and as a DIY project.
This Module is currently available.
VCF based on ARP 4023
Serious? well... it is based on the ARP 4023 and will make the room shake or scream like nails on chalkboard and everything in between. Makes a nice quadrature oscillator too.
These merchants probably sell this module. Huh?
Nonlinearcircuits Serious Filter