Secret-Knock Gumball Machine

Make a cute candy vending machine that only dispenses treats when you knock the secret rhythm on its front panel. Read more »
Make a cute candy vending machine that only dispenses treats when you knock the secret rhythm on its front panel. Read more »
The Stirling engine has long captivated inventors and dreamers. Here are complete plans for building and operating a two-cylinder model that runs on almost any high-temperature heat source. Stirling engines are external combustion engines, which means no combustion takes place inside the engine and there’s no need for intake or... Read more »