Dual Ring Modulators with input level and polarity, CV over quadrant, and wavefolding
5U version adds Limiter switches, which limit the output signals to 10Vpp regardless of the Quadrant position -- without the limiter, the -2 and +2 quadrant settings tend to amplify the signal to about twice the input magnitude, but the limiter forces the amplitude of the output to be constant.
https://www.youtube.com/watch?v=AkRMpsEvodM
This Module is currently available.
$350