Here's a detailed description by Eleanor Fontaine of using the Hex VCF Resonance to cause the six filters to self-oscillate. Using the Frequency controls enables you to set up a different oscillator for each string!
The cool part is that once you're set up each channel, you can control them with your guitar envelope via the Hex EF-Gate-Trigger or an external waveform generator. Pinging the filter through the CVs will create all kinds of new sounds!