Solenoids are everywhere. They open the water valve in your dishwasher, control the flow of gas in your stove, regulate ink delivery in printers, and play a crucial role under the hood of your car.

In general, a solenoid uses electromagnetic force to move a plunger, thereby converting electric energy into mechanical motion. (“Electromagnetic” means it’s only a magnet when electricity is applied.

[Emiel] aka [The Practical Engineer] makes all kinds of fun projects in his fully-featured shop, and one of his tangents has been building a series of solenoid engines. These engines mimic the ...