You’ve heard about the many different snake oil concoctions shilled by con men over the centuries, but did you know that inventors created a variety of machines for similar purposes? The most well-known example is probably the belt vibrator, which purported to induce weight loss. In Argentina during the 1930s, Juan Baigorri Velar claimed to have constructed a functioning rainmaking machine. To pay homage, Roni Bandini used an Arduino to create a replica of the legendary Argentinian rainmaking machine.

Velar’s rainmaking machine almost certainly didn’t work and was either an outright hoax, or the result of misguided optimism masking coincidence. Velar supposedly demonstrated the machine and it was reported as successful at the time, but he never published details about the machine or its operating principles. It was never proven under scientific conditions and no modern experts believe that it could actually summon rainfall. Even today, weather manipulation is very controversial and difficult to perform.

Because details about the original machine are so lacking, Bandini had a lot of freedom for his recreation. But he did try to keep it as accurate as possible, with the notable exception of the radioactive material — including that could be dangerous. The primary component here is an Arduino Nano 33 BLE Sense development board. Other components include a relay, a Peltier cooling cell, an electromagnet, and an analog meter.

In reality, this rainmaking machine isn’t really doing anything except monitoring barometric pressure (through the Arduino’s onboard sensor) and cooling the surface of the Peltier cell. But it sure looks the part. Bandini did a fabulous job with the enclosure, controls, and overall design aesthetic, which looks like something cobbled together by a mad scientist in the 1930s.