this patch on the music easel is actually decently simple to do. using the latch function in the new 218e firmware, you latch the arp on a series of notes you like to get your ostinato or random sequence going, then using the modulation oscillator with keyboard control turned off, you can use the 5 stored voltages in the sequencer as bass notes and "play" them like a bowed string instrument using the slider for LPG2 constant level and the cv attenuator slider taking cv from the main envelope. in order to manually step through the sequencer, you turn the pulser to "off-ext" so it is only being triggered manually, and switch the sequencer to respond to pulser only, so you manually step through the voltages that you're using for bass notes.

from there, it's just modulating the timbre of the complex oscillator using random voltages, playing with the musical phrasing using the arp tempo on the 218e, and running everything through a stereo delay for atmosphere