Every variart piece is open source, you can see exactly how it is drawn from the code.
var spacing = intVariable('spacing', -10, 35);
var numCircles = 6;
var margin = 25;
var startColor = '#581839';
for (var x = margin; x < width; x = x + 100){
for (var y = margin; y < height; y = y + 100){
s.circle(x + margin, y + margin, (width/numCircles) - spacing)
.attr({fill: startColor, opacity: 0.4})
}
}