A Photoshop script to make the sprite-creation process a little more manageable.

GenerateSprite.jsx

// Sprite Generator (Tested on CS5)
// Written by Beau August 2017.

// DESCRIPTION:
// This script will take the width and height of your document, and generate
// a sprite based on the number of images inside the document. The images
// will be automatically aligned. An alignment layer will be placed behind
// each image in the sprite, in case one needs to be changed, modified or
// removed.

// INSTALLATION:
// * Close Photoshop
// * Place this JSX file in your ~\Presets\Scripts relative to where your Photoshop is install on your computer
// * Re open photoshop and click File > Scripts > Generate Sprite 

/*

// BEGIN__HARVEST_EXCEPTION_ZSTRING

<javascriptresource>
<name>$$$/JavaScripts/GenerateSprite/Menu=Generate Sprite</name>
<category>layers</category>
</javascriptresource>

// END__HARVEST_EXCEPTION_ZSTRING

*/

#target photoshop

function ranNum() {
    return Math.floor(Math.random() * 255) + 1;
}

function placeholder() {
	var fillColor = new SolidColor();
	fillColor.rgb.red = ranNum();
	fillColor.rgb.green = ranNum();
	fillColor.rgb.blue = ranNum();

	var baseLayer = doc.layers[layerCount - 1];

	var newLayer = doc.artLayers.add();
	newLayer.name = "aligner " + (i + 1);
	newLayer.move(baseLayer, ElementPlacement.PLACEAFTER);

	doc.selection.selectAll();
	doc.selection.fill(fillColor, ColorBlendMode.VIVIDLIGHT, 40, false);
	doc.selection.deselect();
	
}

function translateLayer(currentLayer, layerIndex) {
	// Why couldn't you just follow CSS?! Left Top Right Bottom
	var currentLayerWidth = currentLayer.bounds[2].value - currentLayer.bounds[0].value;
	var currentLayerHeight = currentLayer.bounds[3].value - currentLayer.bounds[1].value;

	var newLeft = ((docWidth / 2) - (currentLayerWidth / 2) - currentLayer.bounds[0].value);
	var newTop = ((docHeight / 2) - (currentLayerHeight / 2) - currentLayer.bounds[1].value);
	
	var leftTranslate = newLeft + (docWidth * layerIndex);

	currentLayer.translate(leftTranslate, newTop);
}

function translatePlaceholder(allLayers, layerIndex) {
	var layerPlaceholder = allLayers[layerIndex + layerCount];
	var leftTranslate = (docWidth * layerIndex);

	layerPlaceholder.translate(leftTranslate, 0);
	layerPlaceholder.visible = false;
}

function createLayers() {
	docWidth = doc.width.value;
	docHeight = doc.height.value;

	for (i = 0; i < layerCount; i++) {
		placeholder();
	}

	var SpritedocWidth = docWidth * layerCount;
	doc.resizeCanvas(SpritedocWidth, docHeight, AnchorPosition.MIDDLELEFT);

	for (j = 0; j < layerCount; j++) {
		var allLayers = doc.layers
		var currentLayer = allLayers[j];
		translateLayer(currentLayer, j);
		translatePlaceholder(allLayers, j);
	}
}

if (documents.length == 0) { // Check if a document is open
	alert("Please open a document before running the script.") 
} else {
	var doc = app.activeDocument;
	var layerCount = doc.layers.length;

	if (layerCount > 1) {
		createLayers();
	}
}