In "Construct" mode, click to add points, drag between them to add lines. Lines can be a spring (bouncy) or a muscle (gets bigger and smaller). Change the properties of the selected point or line, then "simulate" to make it move. When simulating, you can change gravity, speed, or click and pull your creation around!
SodaScratch - a remake of Sodaplay's Sodaconstructor (soda, 2000), ported from OpenConstructor.