Create multiple image upload fields on any admin options screen using the WordPress media manager overlay.

admin-scripts.js

/**
 * Based off Thomas Griffin's New Media Image Uploader.
 * Thanks for that, man.
 * https://github.com/thomasgriffin/New-Media-Image-Uploader
 */

jQuery( document ).ready( function( $ ) {

	var kol_media_frame;

	$( document.body ).on( 'click', '.kol-field-media-add', function( e ) {

		e.preventDefault();

		$div = $( event.target ).closest( '.kol-field-media' );

		if ( kol_media_frame ) {
			kol_media_frame.open();

			return;
		}

		kol_media_frame = wp.media( {
			frame:    'select',
			multiple: false,
			title:    'Upload Your Image', // may want to replace with wp_localize_script() variable for i18n
			library:  { type: 'image' },
			button:   { text: 'Use This Image' } // same deal as 'title'
		} );

		kol_media_frame.on( 'select', function() {
			selection = kol_media_frame.state().get('selection');
			
			if ( ! selection )
				return;
			
			selection.each( function( attachment ) {
				$div.find( '.kol-field-media-url' ).val( attachment.attributes.sizes.full.url );
			} );
		});

		kol_media_frame.open();
	} );

} );

placeholder.html

<!-- Make sure to wrap the uploader fields in a div that matches the class in the $div variable in your JS. -->

<div class="kol-field-media">

	<input type="text" name="kol[upload_image]" id="kol-upload-image" value="" class="kol-field-media-url regular-text" />

	<input type="button" class="kol-field-media-add button" value="<?php _e( 'Choose Image', 'kol' ); ?>" />

</div>