This is a mechanical sequencer.
The white drum rolls to play. The black strips are made of special rubber that conducts electricity. Both sides of the strips are electrically attached by brass tapes. Each brass tape is attached by brashes that brings the rubber electricity. There are 16 strips, and each strip has a push pin that connects to wire by solder. Each wire is connected to the right-hand brass chips that also are attached by a brush that leads to the synth controller.
As the drum rolls, the push pin to connect to the controller changes. So it works as sequencer. You can change the pich of every tone by shifting the push pin from left to right.
Well, don't expect anything about music quality :-)
For those who prefer electric version of the sequencer, see masa921-san's page and takeda-san's page.