Update: You recently modified the question to ask about 15 or so elements that aren't immediately needed. In this case, with so many non-immediate elements, I would probably consider creating them on the fly when you need them, but always checking for their existence prior so you don't end up re-creating them over and over.
I would just load the element in when the page loads:
<div id="box"></div>
Style it, having it be non-visible by default:
#box {
position: fixed;
top: 10%; left: 10%;
width: 80%; height: 80%;
background: red;
display: none;
}
And then wire-up the logic to show it on some event, perhaps pressing of the spacebar:
var $box = $("#box");
$(document).on({
keydown: function (event) {
if (event.which === 32 && $box.is(":not(:visible)"))
$box.stop().fadeIn();
},
keyup: function (event) {
if (event.which === 32)
$box.stop().fadeOut();
}
});
And voila: http://jsfiddle.net/GfMsd/
Or you could base it off of the clicking of another element, like jsFiddle has done:
$(".toggle").on("click", function (event) {
$("#box").stop().fadeToggle();
});
Demo: http://jsfiddle.net/GfMsd/1/