Here is my guess, based on the gut pictures and description form the company:
1. Input gain stage similar to DOD250 or MXR D+ : uses a reverse log taper as a variable resistor between the inverting input of an OA stage and a capacitor to ground or reference, so that you have a "fat" tone at low gain levels yet a "focused" tone at higher gain settings
2. Body and Air are probably gyrator based band filters (at least the Body, Air might be a shelving filter). My guess here is based on the fact that they used identical W taper potties.
3. Level is probably just a regular voltage divider. Could be a more elaborate circuit, but I won't give them credit so quickly
4. The 4 position switch might be used to change center frequency or Q of the body and air filter.
2c...