hfts_rider,
ваш вариант ))) чуть дополненный
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(document).ready(function(){
function Boxs(width,height,bgColor){
this.width = width;
this.height = height;
this.bgColor = bgColor;
}
var box = new Boxs(250,250,'green');
var box2 = new Boxs(200,200,'yellow');
//Создание коробки
Boxs.prototype.createBox = function(width,height,bgColor){
$('#idDiv').append('<div class="clBox"></div>');
$('.clBox:last').css({'width' : this.width+'px', 'height' : this.height+'px', 'background-color' : this.bgColor, 'margin' : '80px'});
}
box.createBox();
box2.createBox();
});
</script>
</head>
<body>
<div id="idDiv" ></div>
</body>
</html>