Brad Williams

This plugin will display all themes located in wp-content/themes on a page or post in a showcase gallery with theme screenshots and preview links. 
This is a great plugin for designers looking to showcase their work or anyone that wants an easy way to display and preview multiple themes.
New settings page allows you to choose which themes are displayed
For support visit our Theme Showcase Support Forum: 
http://webdevstudios.com/support/forum/wordpress-theme-showcase-plugin/
Features:
<pre><code>* Display a showcase of your themes
* Theme screenshots are displayed with titles and descriptions
* Easily preview all themes loaded in WordPress
* Allow anyone to preview themes, not just administrators
* Works with both WordPress 2.x and WordPress MU (2.7 approved!)
* New settings page lets you pick which themes are displayed
</code></pre>
<h3>Plugin Support</h3>
<a href="http://webdevstudios.com/support/forum/wordpress-theme-showcase-plugin/" title="WordPress Plugins" rel="nofollow ugc">WordPress Theme Showcase Support</a>

WordPress Theme Showcase Plugin

Display themes located in wp-content/themes on a page or post in a showcase gallery with theme screenshots and preview links.

NoreWP

Elementor Designer: A designer/themer’s companion. Showcase your designs in style and allow users to preview before buying/downloading – EDD integrated!
If you are a designer, themer or a website developer who needs to showcase your creation using Elementor then this plugin is for you.
This is an addon to <a href="https://wordpress.org/plugins/elementor/" rel="ugc">Elementor Page Builder</a> which must be installed and activated first.

WordPress Theme Showcase Plugin vs Elementor Designer Lite