Messing with Paper.js for the first time. Cool stuff!

Paper.js sin(balls)

// The amount of circles we want to make:
var count = 79;

// Create a symbol, which we will use to place instances of later:
var path = new Path.Circle({
    center: [0, 0],
    radius: 10,
    fillColor: new Color(1, 1, 0, .5),
    blendMode:'normal'
    
});

var symbol = new Symbol(path);

// Place the instances of the symbol:
for (var i = 0; i < count; i++) {
    // The center position is a random point in the view:
    var center = Point.random() * view.size;
    var placedSymbol = symbol.place(center);
    placedSymbol.scale(i / count);
}

// The onFrame function is called up to 60 times a second:
function onFrame(event) {
    // Run through the active layer's children list and change
    // the position of the placed symbols:
    for (var i = 0; i < count; i++) {
        var item = project.activeLayer.children[i];
        
        // Move the item 1/20th of its width to the right. This way
        // larger circles move faster than smaller circles:
        item.position.x += item.bounds.width / 20;
        item.position.y += Math.sin(item.position.x/8) * 5;

        // If the item has left the view on the right, move it back
        // to the left:
        if (item.bounds.left > view.size.width) {
            item.position.x = -item.bounds.width;
        }
    }
}