Marbles is a source of random gates and voltages, which offers an extensive amount of (voltage) control on all the different flavors of randomness it produces.
The module gives the musician many different ways of imposing structure on the random events generated by the module: synchronization to external clocks, control of the repetition or novelty of the generated material, quantization of the voltages, or randomization of gates or voltages generated by traditional sequencers.
The price is for the blank PCB pictured only. Analog Classics does not provide any support for this open-source project.