My first tries have been two acrylic (=plexiglass) 6mm thick pieces where I milled in two tesla valves and a slot for a piezo buzzer. Screwed both parts together and glued the piezo in. Connected two 3mm (inner diameter) tubes and driving the peizo with an 12V PWM in frequencies up to 60kHz.

It pumped a bit bit overall it was not very successfull, so I continued my research. I also ordered some piezo's with divers used to generate mist which I might try at a later point ofg time.